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The Boy Mechanic: Volume 1 by Popular Mechanics

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into. At the risk of being arrested for killing the squirrels I
have used a small target rifle morning and night, but during my
absence the devastation went on steadily. Last year they destroyed
my entire corn crop. Traps do no good; can't use poison, too
dangerous. But I have solved the difficulty; it's easy.

Shake cayenne pepper over the various vegetables which are being
ruin, and observe results.

** Homemade Electric Stove [31]

The construction of an electric stove is very simple, and it can
be made by any home mechanic having a vise and hand drill. The
body is made of sheet or galvanized iron, cut out and drilled as
shown in Fig. 1.

Each long projection represents a leg, which is bent at right
angles on the center line by placing the metal in the jaws of a
vise and hammering the metal over flat. If just the rim is gripped
in the vise, it will give a rounding form to the lower part of the
legs. The small projections are bent in to form a support for the

The bottom consists of a square piece of metal, as shown in Fig.
2. Holes are drilled near the edges for stove bolts to fasten it
to the bottom projections. Two of the larger holes are used for
the ends of the coiled rod and the other two for the heating-wire
terminals. The latter holes should be well insulated with
porcelain or mica. The top consists of a square piece of metal
drilled as shown in Fig. 3. Four small ears are turned down to
hold the top in place.

One end of the coiled rod is shown in Fig. 4. This illustrates how
two pins are inserted in holes, drilled at right angles, to hold
the coil on the bottom plate. The coiled rod is 3/16 in.

[Illustration: Pattern for Parts of the Electric Stove]

in diameter and 27 in. long. The rod is wrapped with sheet
asbestos, cut in 1/2-in. strips.

The length of the heating wire must be determined by a test. This
wire can be purchased from electrical stores. Stovepipe wire will
answer the purpose when regular heating wire cannot be obtained.
The wire is coiled around the asbestos-covered rod, so that no
coil will be in contact with another coil. If, by trial, the coil
does not heat sufficiently, cut some of it off and try again.
About 9-1/2 ft. of No. 26 gauge heating wire will be about right.
The connection to an electric-lamp socket is made with ordinary
flexible cord, to which is attached a screw plug for making

** Glass-Cleaning Solution [31]

Glass tumblers, tubing and fancy bottles are hard to clean by
washing them in the ordinary way, as the parts are hard to reach
with the fingers or a brush. The following solution makes an
excellent cleaner that will remove dirt and grease from crevices
and sharp corners. To 9 parts of water add 1 part of strong
sulphuric acid. The acid should be added to the water slowly and
not the water to the acid. Add as much bichromate of potash as the
solution will dissolve. More bichromate of potash should be added
as the precipitate is used in cleaning.

The chemicals can be purchased cheaply from a local drug store,
and made up and kept in large bottles. The solution can be used
over and over again. -- Contributed by Loren Ward Des Moines,

** Automatic-Closing Kennel Door [32]

When the neighborhood cats are retired for the night and there is
nothing more to chase, my fox terrier seems to realize that his

[Illustration: Diagram of Closing Door]

for the day is over and begs to be put in his kennel that he may
not bark at the moon as some dogs are apt to do. This necessitates
my putting him out at a time when it may not be convenient.
Frequently in stormy weather this is a disagreeable duty and I
found a way to obviate it by making a trapdoor device for his
kennel as shown in the sketch whereby he may lock himself in when
he crosses the threshold.

The outer half A of the hinged trapdoor is made heavier than the
inner half B by a cleat, C, and a strip, D, to cause the door to
swing shut. The tripper stick E is set between cleats C and F to
hold the door open. When the dog steps on the inner half of the
trapdoor B, it falls to stop G, releasing tripper stick E (which
is heavier on the top end H) to cause it to fall clear of the path
of the trapdoor. The door then swings shut in the direction of the
arrow, the latch I engaging a slot in the door as it closes, and
the dog has locked himself in for the night. The latch I is made
of an old-fashioned gate latch which is mortised in the bottom
joist of the kennel. When releasing the dog in the morning the
door is set for the evening.
--Contributed by Victor Labadie, Dallas, Texas.

** Polishing Cloths for Silver [32]

Mix 2 lb. of whiting and 1/2 oz. of oleic acid with 1 gal. of
gasoline. Stir and mix thoroughly. Soak pieces of gray outing
flannel of the desired size--15 by 12 in. is a good size--in this
compound. Wring the surplus fluid out and hang them up to dry,
being careful to keep them away from the fire or an open flame.
These cloths will speedily clean silver or plated ware and will
not soil the hands.

In cleaning silver, it is best to wash it first in hot water and
white soap and then use the polishing cloths. The cloths can be
used until they are worn to shreds. Do not wash them. Knives,
forks, spoons and other small pieces of silver will keep bright
and free from tarnish if they are slipped into cases made from the
gray outing flannel and treated with the compound.

Separate bags for such pieces as the teapot, coffee pot, hot-water
pot, cake basket and other large pieces of silverware will keep
them bright and shining.
--Contributed by Katharine D. Morse, Syracuse, N. Y.

** A Book-Holder [32]

Books having a flexible back are difficult to hold in an upright
position when copying from them. A makeshift combination of
paperweights and other books is often used, but with
unsatisfactory results.

[Illustration: Fig 2. Box Corner Makes a Book Holder]

The book-holder shown in the sketch will hold such books securely,
allow the pages to be turned easily and conceal the smallest
possible portion of each page.

The holder can be cut out of a box corner and fitted with two
screw eyes, which have the part shown by the dotted lines at A
(Fig. 1) removed. The length of the back board determines the
slope for the book rest.
--Contributed by James M. Kane, Doylestown, Pa.

** Clamping a Cork [33]

It is aggravating to continually break the cork of the stock
mucilage bottle because of its sticking to the neck of the bottle
after a supply has been poured out. If a stove bolt is inserted
lengthwise through the cork with a washer on each end and the nut
screwed up tightly, as shown in the sketch, the cork may be made
to last longer than the supply of mucilage and can be placed in a
new bottle and used over and over again.

[Illustration: Cork Clamp]

** Withdrawing Paper from under an Inverted Bottle [33]

Invert a bottle on a piece of paper near the edge of a table top
and ask anyone to remove the paper without overturning the bottle.
They will at once jerk the paper with the result that the bottle
will turn over. To remove the paper just strike the table top with
your right fist while pulling the paper slowly with your left
hand. As you strike the table the bottle will jump and release the
--Contributed by Maurice Baudier, New Orleans, La.

** Emergency Tire Repair [33]

A bone collar button makes a good substitute for a plug in
repairing a puncture in a single-tube bicycle tire.

** Broom Holder Made of a Hinge [33]

The broom holder shown in the sketch is made of an ordinary hinge
with one wing screwed to the wall. The loose wing has a large hole
drilled in it to receive the handle of the broom. The manner of
holding the broom is plainly shown in the sketch.
--Contributed by Theodore L. Fisher; Waverly, Ill.

[Illustration: Broom Holder]

** Making Proofs before the Negative Dries [33]

A correspondent of Camera Craft makes proofs from his developed,
but unfixed, negatives, by squeezing a sheet of wet bromide paper
into contact with the wet film and giving an exposure several
times longer than would be required under ordinary conditions,
using the paper dry. If the developer is well rinsed out of the
film, the exposure to artificial light necessary to make a print
will have no injurious effect upon the negative, which is, of
course, later fixed and washed as usual.

** Flower-Pot Stand [33]

A very useful stand for flower pots can be made of a piece of
board supported by four clothes hooks. The top may be of any size
suitable for the flower pot. The hooks which serve as legs are
fastened to the under side of the board in the same manner as
fastening the hook to a wall.
--Contributed by Oliver S. Sprout, Harrisburg, Pa.

[Illustration: Flower-pot Stand]

** A Line Harmonograph [34]

[Illustration: Harmonograph]

As an apparatus capable of exciting interest, probably nothing so
easily constructed surpasses the harmonograph. Your attention will
be completely absorbed in the ever changing, graceful sweep of the
long pendulum, the gyrations of which are faithfully recorded in
the resulting harmonogram.

A careless impetus given to the pendulum may result in a very
beautiful harmonogram, but you may try innumerable times to
duplicate this chance record without success. No two hamonograms
are exactly alike. The harmonograph, while its pendulum swings in
accordance with well known natural laws, is exceedingly erratic
when it comes to obeying any preconceived calculations of its
operator. In this uncertainty lies the charm. If time hangs
heavily or a person is slightly nervous or uneasy, a harmonograph
is a good prescription.

The prime essential in a well working harmonograph is a properly
constructed universal joint. Where such a joint is made with
pivots for its bearings, one pair of pivots are very liable to
have more friction than the other, which retards the movement and
causes the harmonograph to undergo a continuous change of axis. To
obviate this difficulty, the joint should be made similar to those
used on scales. The general appearance of such a joint is shown in
the first illustration, Fig. 1. Stirrups A and B are made of 7/8
by 1/4-in. metal. Holes are drilled in each end of these stirrups
and filed out as shown at C. The two holes shown in the center of
the stirrup A are drilled to fasten the apparatus to the ceiling.
Two corresponding holes are drilled in B to fasten the long
pendulum F to the joint. The cross of the joint D has the ends
shaped as shown at E. The rounded shoulder on E is to prevent the
cross from becoming displaced by a jar or accident. The ends of
the cross are inserted through the holes C of the stirrups, then
slipped back so the knife edges engage in the V-shaped holes of
the stirrups. The cross must be so made that the knife edges will
be in the same plane. This can be determined by placing two of the
knife edges on the jaws of a vise and then laying two rules across
the other two edges. The rules should just touch the jaws of the
vise and the two knife edges of the cross. This makes a universal
joint almost free from friction and, what is most important,
prevents the pendulum from twisting on its own axis.

The pendulum F should be made of ash or oak, 1-3/4 by 2 in., with
a length depending on the height of the ceiling. A length of 7 ft.
is about right for a 10-ft. ceiling.

A small table or platform, K, as shown in the lower part of Fig.
1, is fastened to the lower end of the pendulum as a support for
the cards on which harmonograms are made. A weight, G, of about 30
or 40 lb.-a box filled with small weights will do--is attached to
the pendulum just above the table. Another weight of about 10 lb.
is attached as shown at H. A pedestal, J, provides a means of
support for the stylus. The stylus arm should have pin-point
bearings, to prevent any side motion.

The length of the short pendulum H, which can be regulated, as
shown in Fig. 1, should bear a certain and exactly fixed relation
to the length of the main pendulum, for the swinging times of
pendulums are inversely proportionate to their lengths, and unless
the shorter pendulum is, for instance, exactly one-third,
one-fourth, one-fifth, etc., as long as the other, that is, makes
respectively 3, 4 or 5 swings to one swing of the long pendulum,
they will not harmonize and a perfect harmonogram is not obtained.

A good stylus to contain the ink is easily made from a glass tube
1/4 in. in diameter. Heat the tube in an alcohol or Bunsen flame
and then, by drawing the two portions apart and twisting at the
same time, the tube may be drawn to a sharp point. An opening of
any desired size is made in the point by rubbing it on a
whetstone. Owing to the fact that the style of universal joint
described has so little friction, the stylus point must be very

[Illustration: Lines Made with the Harmonograph]

fine, or the lines will overlap and blur. A small weight, such as
a shoe buttoner, placed on the arm near the stylus will cause
enough friction to make the pendulum "die" faster and thus remedy
the trouble.
--Contributed by Wm. R. Ingham, Rosemont, Arizona.

** Cutting Circular Holes in Thin Sheet Metal [35]

In arts and crafts work, occasion often arises to cut a perfectly
circular hole in sheet copper or brass. To saw and file it out
takes time and skill. Holes up to 3 in. in diameter can be cut
quickly and accurately with an ordinary expansive bit.

Fasten the sheet metal to a block of wood with handscrews or a
vise. Punch a hole, with a nail set or punch, in the center of the
circle to be cut, large enough to receive the spur of the
expansive bit. A few turns of the brace will cut out the circle
and leave a smooth edge.
--Contributed by James T. Gaffney, Chicago.

** Key Card for Writing Unreadable Post Cards [35]

A key card for use in correspondence on postals that makes the
matter unreadable unless the recipient has a duplicate key card is
made as follows: Rule two cards the size of postal, one for the
sender and one for the receiver, dividing them into quarters.
These quarters are subsequently divided into any convenient number
of rectangular parts-six in this case.

These parts are numbered from one to six in each quarter beginning
at the outside corners and following in the same order in each
quarter. Cut out one rectangle of each number with a sharp knife,
distributing them over the whole card. Then put a prominent figure
1 at the top of one side, 2 at the bottom and 3 and 4 on the other
side. The numbering and the cutouts are

[Illustration: The Key Card]

shown in Fig. 1. The two key cards are made alike.

The key card is used by placing it over a postal with the figure 1
at the top and writing in the spaces from left to right as usual,
Fig. 3, then put 2 at the top, Fig. 4, and proceed as before, then
3 as in Fig. 5, and 4 as in Fig. 6. The result will be a jumble of
words as shown in Fig. 2, which cannot be read to make any sense
except by use of a key card.
--Contributed by W.J. Morey, Chicago.

** Homemade Carpenter's Vise [36]

The sketch shows an easily made, quick-working wood vise that has
proved very satisfactory. The usual screw is replaced by an open
bar held on one end by a wedge-shaped block,

[Illustration: Vise Made Entirely of Wood]

and the excess taken up on the other end by an eccentric lever.
The wedge is worked by a string passing through the top of the
bench and should be weighted on the other end to facilitate the
automatic downward movement.

The capacity of the vise, of course, depends on the size and shape
of the wedge-shaped block.
--Contributed by J.H. Cruger, Cape May City, N.J.

** Toning Blue on Bromide and Platinum [36]

After some experimenting to secure a blue tone on bromide prints,
a correspondent of the Photographic Times produced a very pleasing
bluish green tint by immersing the prints in a solution composed
of 30 gr. of ferricyanide of potash, 30 gr. citrate of iron and
ammonia, 1/2 oz. acetic acid and 4 oz. of water. After securing
the tint desired, remove the prints, rinse them in clean water for
a few minutes, and then place them in a dilute solution of
hydrochloric acid. Wash the prints thoroughly and hang them up
with clips to dry.

** Cutting Loaf Bread [36]

When cutting a loaf of bread do not slice it from the outer
crusted end. Cut through the center, then cut slices from the
center toward the ends. The two cut surfaces can be placed
together, thus excluding the air and keeping the bread fresh as
long as there is any left to slice.
--Contributed by L. Alberta Norrell, Augusta, Ga.

** How to Make an Electric Toaster [37]

The electric toaster shown in the sketch is not hard to make. The
framework comprising the base and the two uprights may be made
either of hardwood or asbestos board, says Popular Electricity. If
constructed of the former, the portion of the base under the coil,
and the inside surfaces of the two uprights should be covered with
a 1/8-in. sheet of well made asbestos paper, or thin asbestos
board may be substituted for this lining. Asbestos board is to be
preferred, and this material in almost any degree of hardness may
be purchased. It can be worked into shape and will hold wood
screws. The detail drawing gives all dimensions necessary to shape
the wood or asbestos board.

After preparing the base and uprights, drill 15 holes, 1/4 in.
deep, into the inside face of each upright to support the No. 6
gauge wires shown. The wires at the top and bottom for holding the
resistance wire are covered with asbestos paper and the holes for
these wires are 3/4 in. from the top and bottom, respectively, of
the uprights. The wires that form the cage about the heater coil
and are used for a support for the toast are 15 pieces of No. 6
gauge iron wire each 8 in. long. The screws that hold the uprights
in position should have the heads countersunk on the under side of
the base. The binding-posts should now be set in position and
their protecting covering

[Illustration: Detail of Toaster]

containing the reinforced cord left until the other parts are

To assemble, secure one upright in position using 1-1/2 in.
wood-screws. Place the other upright where it belongs without
fastening it and put the stretcher wires for holding the
resistance wire in place. Put the asbestos paper on these and with
the assistance of a helper begin winding on the heater coil.

[Illustration: Toaster Complete]

Use 80 ft. of 18-per-cent No. 22 gauge German-silver wire. Wind
the successive turns of wire so they will not touch each other and
fasten at each end with a turn or two of No. 16 gauge copper wire.
When this is complete have the helper hold the stretcher wires
while you tip the unfastened upright out and insert the wires of
the cage, then fasten the upright in place.

The wire from the binding-posts to the coil may be what is known
underwriters' wire or asbestos-covered wire No. 14 gauge, which is
held in place by double-headed tacks containing an insulation at
the head. These may be procured from electrical supply houses.
Connect the reinforced cord and terminals to the binding screws
and fasten the cover in place. This toaster will take four amperes
on 110-volt circuit.

** Cabinet for the Amateur's Workshop [37]

One of the most convenient adjuncts to an amateur's workbench is a
cabinet of some sort in which to keep nails, rivets, screws, etc.,
instead of leaving them scattered all about the bench. A very
easily made cabinet for this purpose is shown in the accompanying
illustration. The case may be made of 1/2-in. white pine or white
wood of a suitable size to hold the required number of drawers
which slide on strips of the same material, cut and dressed 1/2
in. square. The drawers are made of empty cigar boxes of uniform

[Illustration: Empty Cigar Boxes Used for Drawers]

which, if one is not a smoker, may be readily obtained from any
cigar dealer, as they are usually thrown away when empty.

Small knobs may be added if desired, but these are not necessary,
as the spaces shown between the drawers give ample room to grasp
them with the fingers. Labels of some kind are needed, and one of
the neatest things for this purpose is the embossed aluminum
label, such as is stamped by the well known penny-in-the-slot
machines to be found in many railroad stations and amusement
--Contributed by Frederick E. Ward, Ampere, N. Y.

** Uncurling Photographs [38]

Photograph prints can be kept from curling when dry, by giving
them the same treatment as was once used on films. Immerse for 5
minutes in a bath made by adding 14 oz. of glycerine to 16 oz. of

** Soldering for the Amateur [38]

Successful soldering will present no serious difficulties to
anyone who will follow a few simple directions. Certain metals are
easier to join with solder than others and some cannot be soldered
at all. Copper, brass, zinc, tin, lead, galvanized iron, gold and
silver or any combination of these metals can be easily soldered,
while iron and aluminum are common metals that cannot be soldered.

It is necessary to possess a soldering copper, a piece of solder,
tinner's acid, sandpaper or steel wool, a small file and a piece
of sal ammoniac. If the soldering copper is an old one, or has
become corroded, it must be ground or filed to a point. Heat it
until hot (not red hot), melt a little solder on the sal ammoniac,
and rub the point of the copper on it, turning the copper over to
thoroughly tin the point on each face. This process is known as
tinning the iron and is very necessary to successful work.

After the copper is tinned you may place it in the fire again,
being careful about the heat, as too hot an iron will burn off the

The parts to be soldered must be thoroughly cleaned by
sandpapering or the use of steel wool until the metal shows up
bright. Then apply the acid only to the parts to be soldered with
a small stiff brush or a small piece of cloth fastened to a stick,
or in a bent piece of tin to form a swab.

Tinner's acid is made by putting as much zinc in commercial
muriatic acid as will dissolve. This process is best accomplished
in an open earthenware dish. After the acid has ceased to boil and
becomes cool it may be poured into a wide-mouthed bottle which has
a good top or stopper, and labeled "Poison."

Place the parts to be soldered in their correct position and apply
the hot copper to the solder, then to the joint to be soldered,
following around with the copper and applying solder as is
necessary. In joining large pieces it is best to "stick" them
together in several places to hold the work before trying to get
all around them. A little practice will soon teach the requisite
amount of solder and the smoothness required for a good job.

In soldering galvanized iron, the pure muriatic acid should be
used, particularly so when the iron has once been used. --C. G.
S., Eureka Springs, Ark.

** Washboard Holder [39]

When using a washboard it will continually slip down in the tub.
This is considerable annoyance, especially if a large tub is used.
The washboard can be kept in place with small metal hooks, as
shown in the sketch. Two of these are fastened to the back of

[Illustration: Clip on the Washboard]

the washboard in the right place to keep it at the proper slant.
--Contributed by W. A. Jaquythe, Richmond, California.

** A Mission Bracket Shelf [39]

The shelf consists of six pieces of wood A, B, C, D, E and F. The
material can be of any wood. I have one made of mahogany finished
in natural color, and one made of poplar finished black. The
dimensions given in the detail drawings are sufficient for anyone
to make this bracket. The amount of material required is very
small and can be made from scrap, or purchased from a mill
surfaced and sanded. The parts are put together with dowel pins.
--Contributed by A. Larson, Kenosha, Wis.

[Illustration: Details of the Wall Bracket]

** How to Make a Finger Ring [39]

While the wearing of copper rings for rheumatism may be a foolish
notion, yet there is a certain galvanic action

[Illustration: Tools for Forming the Ring]

set up by the contact of the acid in the system of the afflicted
person with the metal of the ring. Apart from this, however, a
ring may be made from any metal, such as copper, brass and silver,
if such metals are in plate or sheet form, by the following

All the tools necessary are a die and punch which are simple to
make and will form a ring that will fit the average finger. Take a
3/4-in. nut, B, Fig. 1, and drill out the threads. This will leave
a clear hole, 7/8 in. in diameter, or a hole drilled the desired
size in a piece of iron plate will do as well. Countersink the top
of the hole so that the full diameter of the countersink will be
1-1/4 in. This completes the die. The punch A, is made of a piece
of 5/8 in. round iron, slightly rounded on the end so that it will
not cut through the metal disk. The dimensions shown in Fig. 1 can
be changed to suit the size of the finger to be fitted.

The metal used should be about 1/16 in. thick and 1-1/4 in. in
diameter. Anneal it properly by heating and plunging in water. Lay
it on the die so that it will fit nicely in the countersink and
drive it through the hole by striking the punch with a hammer.
Hold the punch as nearly central as possible when starting to
drive the metal through the hole. The disk will come out pan
shaped, C, and it is only necessary to remove the bottom of the
pan to have a band which will leave a hole 5/8 in. in diameter and
1-1/4 in. wide. Place the band, D, Fig. 2, on a stick so that the
edges can be filed and rounded to shape. Finish with fine emery
cloth and polish. Brass rings can be plated when finished.
--Contributed by H. W. Hankin, Troy, N. Y.

** How to Bind Magazines [40]

A great many readers of Popular Mechanics Magazine save their
copies and have them bound in book form and some keep them without
binding. The bound volumes make an attractive library and will
always be valuable works of reference along mechanical lines. I
bind my magazines at home evenings, with good results. Six issues
make a well proportioned book, which gives two bound volumes each

The covers of the magazines are removed, the wire binders pulled
out with a pair of pliers and the advertising pages removed from
both sides, after which it will be found that the remainder is in
sections, each section containing four double leaves or sixteen
pages. These sections are each removed in turn from the others,
using a pocket knife to separate them if they stick, and each
section is placed as they were in the magazine upon each preceding
one until all six numbers have been prepared. If started with the
January or the July issue, the pages will be numbered
consecutively through the entire pages of the six issues.

The sections are then prepared for sewing. They are evened up on
the edges by jarring on a flat surface. They are then placed
between two pieces of board and all clamped in a vise. Five cuts,
1/8 in. deep, are made with a saw across the back of the sections,
as shown in Fig. 1. Heavy plain paper is used for the flyleaves.
The paper is cut double the same as the leaves comprising the
sections, making either one or two double sections for each side
as desired.

A frame for sewing will have to be made as shown in Fig. 2 before
the work can be continued on the book. The frame is easily made of
four pieces of wood. The bottom piece A should be a little larger
than the book. The two upright pieces B are nailed to the outside
edge, and a third piece, C, is nailed across the top. Small nails
are driven part way into the base C to correspond to the saw cuts
in the sections. A piece of soft fiber string is stretched from
each nail to the crosspiece C and tied.

Coarse white thread, size 16 or larger, is used for the sewing
material. Start with the front of the book. Be sure that all
sections are in their right places and that the flyleaves are
provided in the front and back. Take the sections of the flyleaves
on top, which should be notched the same as the saw cuts in the
book sections, and place them against the strings in the frame.
Place the left hand on the inside of the leaves where they are
folded and start a blunt needle, threaded double, through the
notch on the left side of the string No. 1 in Fig. 2. Take hold of
the needle with the right hand and pass it to the left around the
string No. 1, then back through the notch on the right side.
Fasten the thread by tying or making a knot in the end and passing
the needle through it. After drawing the thread tightly, pass the
needle through the notch on the left side of the string No. 2,
passing it around the string and tying in the same manner as for
No. 1. Each section is fastened to the five strings in the same
manner, the thread being carried across from each tie from No. 1
to 2 then to 3 and so on

[Illustration: Frame for Sewing Sections]

until all strings are tied. The string No. 5 is treated in the
same manner only that the needle is run through on the left side
of the string a second time, leaving the needle on the outside in
position for the next section, which is fastened the same as the
first, the needle being passed through the notch on the right side
of the string No. 5, and then to string No.4, passing around on
the right side and back on the left and so on. Keep the thread
drawn up tightly all the time.

After the sewing is completed cut the strings, allowing about 2
in. of the ends extending on each side. The fibers of these ends
are separated and combed out so that they can be glued to the
covers to serve as a hinge. A piece of cheesecloth is cut to the
size of the back and glued to it. Ordinary liquid glue is the best
adhesive to use.

Procure heavy cardboard for the covers and cut two pieces 1/2 in.
longer and just the same width as the magazine pages. The covering
can be of cloth, leather or paper according to the taste and
resources of the maker. The covering should be cut out 1 in.
larger on all edges than both covers and space on the back. Place
the cardboard covers on the book, allowing a margin of 1/4 in. on
all edges except the back, and measure the distance between the
back edges of the covers across the back of the book.

Place the cardboard covers on the back of the covering the proper
distance apart as measured for the back, and mark around each one.
Spread thin coat of glue on the surface of each and lay them on by
the marks made. Cut a notch out of the covering so it will fold
in, and, after gluing

[Illustration: The Bound Book]

a strip of paper to the covering between the covers to strengthen
the back, fold over the outside edges of the covering and glue it
down all around.

Place the cover on the book in the right position, glue the hinges
fast to the inside of the covers, then glue the first flyleaf to
the inside of the cover on both front and back and place the whole
under a weight until dry.
--Contributed by Clyde E. Divine, College View, Nebr.

** Metal Coverings for Leather Hinges [41]

A method of making a leather hinge work as well as an ordinary
steel butt is to cover the wings with sheet metal. The metal can
be fastened with nails or screws over the parts of the leather
attached to the wood. Tinplate, iron

[Illustration: Metal Parts Screwed on Leather Hinge]

hoops, zinc or thin brass cut in neat designs will make a leather
hinge appear as well as a metal hinge.
--Contributed by Tom Hutchinson, Encanto, Cal.

** Removing Plaster from Skin [41]

A hot-water bottle held against a porous plaster will assist in
quickly removing it from the skin.

** How to Make a Cheap Bracket Saw [42]

For the frame use 3/8-in. round iron, bending it as shown in the
diagram and filing a knob on each end, at opposite sides to each
other, on which to hook the blade. For the blade an old

[Illustration: Hacksaw Frame and Blade]

spring or a clock spring will do nicely. Heat the spring enough to
take some of the temper out of it, in order to drill the holes in
the ends, as shown, and file in the teeth. Make the blade 12 in.
long, with 10 teeth to the inch. A and B show how the blade fits
on the frame. -Contributed by Willard J. Hays, Summitville, Ohio.

** How to Make a Cannon [42]

A cannon like the one in the cut may be made from a piece of 1-in.
hydraulic pipe, A, with a steel sleeve, B, and a long thread plug,
C. Be sure to get hydraulic pipe, or double extra heavy, as it is
sometimes called, as common gas pipe is entirely too light for
this purpose. Don't have the pipe too long or the cannon will not
make as much

[Illustration: Toy Cannon]

noise. Seven or eight inches is about the right length for a 1-in.
bore. Screw the plug and pipe up tightly and then drill a 1/16-in.
fuse hole at D.

If desired the cannon may be mounted on a block of wood, F, by
means of a U-bolt or large staple, E.
--Contributed by Carson Birkhead, Moorhead, Miss.

** Controller for a Small Motor [42]

An easy way of making a controlling and reversing device for small
motors is as follows:

Cut a piece of wood (A) about 6 in. by 4-1/2 in., and 1/4 in.
thick, and another piece (B) 6 in. by 1 in., and 1/4 in. thick.
Drive a nail through this near the center for a pivot (C). To the
under side of one end nail a copper brush (D) to extend out about
an inch. On the upper side, at the same end, nail another brush
(E) so that it projects at both sides and is bent down to the
level of the end brush. Then on the board put

[Illustration: Reverse for Motor]

a semi-circle of brass-headed tacks as shown at F, leaving a small
space at the middle and placing five tacks on either side, so that
the end brush will come in contact with each one. Connect these
tacks on the under side of the board with coils of German-silver
wire, using about 8 in. of wire to each coil. Fix these by
soldering or bending over the ends of the tacks. Then nail two
strips of copper (G) in such position that the side brush will
remain on the one as long as the end brush remains on the tacks on
that side.

Put sides about 1-1/2 in. high around this apparatus, raising the
board a little from the bottom to allow room for the coil. A lid
may be added if desired. Connect up as shown.
--Contributed by Chas. H. Boyd, Philadelphia.

** How to Make a Simple Water Rheostat [43]

[Illustration: Wiring Plan for Water Rheostat]

The materials necessary are: One 5-point wood-base switch, 4 jars,
some sheet copper or brass for plates, about 5 ft. of
rubber-covered wire, and some No. 18 gauge wire for the wiring.

The size of the jars depends on the voltage. If you are going to
use a current of low tension, as from batteries, the jars need not
be very large, but if you intend to use the electric light current
of 110 voltage it will be necessary to use large jars or wooden
boxes made watertight, which will hold about 6 or 7 gal. Each jar
to be filled with 20 parts water to 1 part sulphuric acid. Jars
are set in a row in some convenient place out of the way.

Next cut out eight copper or brass disks, two for each jar. Their
size also depends on the voltage. The disks that are placed in the
lower part of the jars are connected with a rubber covered wire
extending a little above the top of the jar.

To wire the apparatus, refer to the sketch and you will see that
jar No. 1 is connected to point No. 1 on switch; No. 2, on No. 2,
and so on until all is complete and we have one remaining point on
switch. Above the jars place a wire to suspend the other or top
disks in the solution. This wire is also connected to one terminal
on the motor and to remaining point on switch. The arm of the
switch is connected to one terminal of battery, or source of
current, and the other terminal connected direct to remaining
terminal of motor.

Put arm of switch on point No. 1 and lower one of the top disks in
jar No. 1 and make contact with wire above jars. The current then
will flow through the motor. The speed for each point can be
determined by lowering top disks in jars. The top disk in jar No.
2 is lower down than in No. 1 and so on for No. 3 and No. 4. The
connection between point No. 5 on switch, direct to wire across
jars, gives full current and full speed.

** How to Build a Toboggan Sled [44]

The first object of the builder of a sled should be to have a
"winner" both in speed and appearance. The accompanying
instructions for building a sled are designed to produce these

The sled completed should be 15 ft. 2 in. long by 22 in. wide,
with the cushion about 15 in. above the ground. For the baseboard
select a pine board 15 ft. long, 11 in. wide and 2 in. thick, and
plane it on all edges. Fit up the baseboard with ten oak
foot-rests 22 in. long, 3 in. wide and 3/4 in. thick. Fasten them
on the under side of the baseboard at right angles to its length
and 16 in. apart, beginning at the rear. At the front 24 or 26 in.
will be left without cross bars for fitting on the auto front. On
the upper side of the cross bars at their ends on each side screw
a piece of oak 1 in. square by 14 ft. long. On the upper side of
the baseboard at its edge on each side screw an oak strip 3 in.
wide by 3/4 in. thick and the length of the sled from the back to
the auto front. These are to keep the cushion from falling out.
See Fig. 1. For the back of the sled use the upper part of a
child's high chair, taking out the spindles and resetting them in
the rear end of the baseboard. Cover up the outside of the
spindles with a piece of galvanized iron.

The construction of the runners is shown by Figs. 2 and 3. The
stock required for them is oak, two pieces 30 in. by 5 in. by
1-1/4 in., two pieces 34 in. by 5 in. by 1-1/4 in., two pieces 14
in. by 6 in. by 2 in., and four pieces 14 in. by 2 in. by 1 in.
They should be put together with large screws about 3 in. long.
Use no nails, as they are not substantial enough. In proportioning
them the points A, B and C, Fig. 2, are important. For the front
runners these measurements are: A, 30 in.; B, 4 in.; C, 15-1/2
in., and for the rear runners: A, 34 in.; B, 7 in. ; C, 16-1/2 in.
The screw eyes indicated must be placed in a straight line and the
holes for them carefully centered. A variation of 1/16 in. one way
or another would cause a great deal of trouble. For the steel
runners use 3/8 in. cold-rolled steel flattened at the ends for
screw holes. Use no screws on the running surface, however, as
they "snatch" the ice.

The mechanism of the front steering gear is shown at Fig. 3. A
3/4-in. steel rod makes a good steering rod. Flatten the steering
rod at one end and sink it into the wood. Hold it in place by
means of an iron plate drilled to receive the rod and screwed to
block X. An iron washer, Z, is used to reduce friction; bevel
block K to give a rocker motion. Equip block X with screw eyes,
making them clear those in the front runner, and bolt through. For
the rear runner put a block with screw eyes on the baseboard and
run a bolt through.

Construct the auto front (Fig. 4) of 3/4-in. oak boards. The
illustration shows how to shape it. Bevel it toward all sides and
keep the edges sharp, as sharp edges are best suited for the brass
trimmings which are to be added. When the auto front is in place
enamel the sled either a dark maroon or a creamy white. First
sandpaper all the wood, then apply a coat of thin enamel. Let
stand for three days and apply another coat. Three coats of enamel
and one of thin varnish will make a fine-looking sled. For the
brass trimmings use No. 27 B. & S. sheet brass 1 in. wide on all
the front edges and pieces 3 in. square on the cross bars to rest
the feet against. On the door of the auto front put the monogram
of the owner or owners of the sled, cutting it out of sheet brass.

For the steering-wheel procure an old freight-car "brake" wheel,
brass plated. Fasten a horn, such as used on automobiles, to the

Make the cushion of leather and stuff it with hair. The best way
is to get some strong, cheap material, such as burlap, sew up one
end and make in

[Illustration: Construction a "Winner" Toboggan Sled]

the form of an oblong bag. Stuff this as tightly as possible with
hair. Then get some upholstery buttons, fasten a cord through the
loop, bring the cord through to the underside of the cushion, and
fasten the button by slipping a nail through the knot. Then put a
leather covering over the burlap, sewing it to the burlap on the
under side. Make the cushion for the back in the same way. On top
of the cushion supports run a brass tube to serve the double
purpose of holding the cushion down and affording something to
hold on to.

If desired, bicycle lamps may be fastened to the front end, to
improve the appearance, and it is well to have a light of some
kind at the back to avoid the danger of rear-end collisions.

The door of the auto front should be hinged and provided with a
lock so that skates, parcels, overshoes, lunch, etc. may be stowed
within. A silk pennant with a monogram adds to the appearance.

If desired, a brake may be added to the sled. This can be a
wrought-iron lever 1-1/2 in. by 1/2 in. by 30 in. long, so pivoted
that moving the handle will cause the end to scrape the ice. This
sled can be made without lamps and horn at a cost of about $15, or
with these for $25, and the pleasure derived from it well repays
the builder. If the expense is greater than one can afford, a
number of boys may share in the ownership.

** Burning Inscriptions on Trees

Scrape off the bark just enough to come to the first light under
coating, which is somewhat moist. With a lead pencil make an
outline of the inscription to be burnt on the tree and bring, the
rays of a large magnifying glass not quite to a fine focus on the
same. The tree will be burnt along the pencil marks, and if the
glass is not held in one spot too long, the inscription will be
burnt in as evenly as if it had been written.
--Contributed by Stewart H. Leland, Lexington, Ill.

** How to Make Small Gearwheels Without a Lathe [46]

To make small models sundry small gears and racks are required,
either cut for the place or by using the parts from an old clock.
With no other tools than a hacksaw, some files, a compass,

[Illustration: Making Model Wheels]

and with the exercise of a little patience and moderate skill,
very good teeth may be cut on blank wheels.

First take the case of a small gearwheel, say 1 in. outside
diameter and 1/16 in. thick, with twenty-four teeth. Draw a circle
on paper, the same diameter as the wheel. Divide the circumference
into the number of parts desired, by drawing diameters, Fig. 1.
The distance AB will be approximately the pitch. Now describe a
smaller circle for the base of the teeth and halfway between these
circles may be taken as the pitch circle.

Now describe a circle the same size as the largest circle on a
piece of 1/16-in. sheet metal, and having cut it out and filed it
up to this circle, fasten the marked-out paper circle accurately
over it with glue. Saw-cuts can now be made down the diameters to
the smaller circle with the aid of a saw guide, Fig. 2, made from
1/16-in. mild steel or iron. This guide should have a beveled
edge, E, from F to G, to lay along the line on which the saw-cut
is to be made. The straight-edge, CD, should be set back one-half
the thickness of the saw-blades, so that the center of the blade,
when flat against it, will be over the line FG. A small clearance
space, FC, must be made to allow the teeth of the saw to pass.

The guide should then be placed along one of the diameters and
held in position until gripped in the vise, Fig. 3. The first
tooth may now be cut, care being taken to keep the blade of the
saw flat up to the guiding edge. The Model Engineer, London, says
if this is done and the saw-guide well made, the cut will be
central on the line, and if the marking-out is correct the teeth
will be quite uniform all the way round. A small ward file will be
needed to finish off the teeth to their proper shape and

In making a worm wheel the cuts must be taken in a sloping
direction, the slope and pitch depending on the slope and pitch of
the worm thread, which, though more difficult, may also be cut
with a hacksaw and file.

A bevel wheel should be cut in the same manner as the spur wheel,
but the cut should be deeper on the side which has the larger
diameter. To cut a rack the pitch should be marked along the side,
and the guide and saw used as before (Fig. 4).

** How to Make Four Pictures on One Plate [46]

Secure two extra slides for the plate holders and cut one corner
out on one

[Illustration: Four Photos on One Plate]

of them, as shown in Fig. 1. Make a hole in the other, as shown in
Fig. 2. With a lead pencil draw on the ground glass one line
vertical and one horizontal, each in the center. This will divide
the ground glass into four equal parts.

Focus the camera in the usual manner, but get the picture desired
to fill only one of the parts on the ground glass. Place the
plate-holder in position and draw the regular slide; substitute
one of the slides prepared and expose in the usual way.

If a small picture is to be made in the lower left-hand corner of
the plate, place the prepared slide with the corner cut, as shown
in Fig. 1. The slide may be turned over for the upper left hand
corner and then changed for slide shown in Fig. 2 for the upper
and lower right-hand corners.

** Electric Blue-Light Experiment [47]

[Illustration: Electric Blue-light]

Take a jump-spark coil and connect it up with a battery and start
the vibrator. Then take one outlet wire, R, and connect to one
side of a 2-cp. electric lamp, and the other outlet wire, B, hold
in one hand, and press all fingers of the other hand on globe at
point A. A bright, blue light will come from the wires in the lamp
to the surface of the globe where the fingers touch. No shock will
be perceptible.

** Interesting Electrical Experiment [47]

The materials necessary for performing this experiment are:
Telephone receiver, transmitter, some wire and some carbons,
either the pencils for arc lamps, or ones taken from old dry
batteries will do.

Run a line from the inside of the house to the inside of some
other building and fasten it to one terminal of the receiver. To
the other terminal fasten another piece of wire and ground it on
the water faucet in the house. If there is no faucet in the house,
ground it with a large piece of zinc.

Fasten the other end to one terminal of the transmitter and from
the other terminal of the same run a wire into the ground. The
ground here should consist either of a large piece of carbon, or
several pieces bound tightly together.

[Illustration: A Unique Battery]

If a person speak into the transmitter, one at the receiver can
hear what is said, even though there are no batteries in the
circuit. It is a well known fact that two telephone receivers
connected up in this way will transmit words between two persons,
for the voice vibrating the diaphragm causes an inductive current
to flow and the other receiver copies these vibrations. But in
this experiment, a transmitter which induces no current is used.
Do the carbon and the zinc and the moist earth form a battery?
--Contributed by Wm. J. Slattery, Emsworth, Pa.

** A Cheap Fire Alarm [47]

An electrical device for the barn that will give an alarm in case
of fire is shown in the accompanying diagram. A is a wooden block,
which is fastened under the loft at a gable end of the barn; B is
an iron weight attached to the string C, and this string passes up
through the barn to the roof, then over a hook or pulley and
across the barn, under the gable, and is fastened to the opposite
end of the barn.

D D are binding posts for electric wires. They have screw ends, as
shown, by which means they are fastened to the wooden block A.
They also hold the brass piece E and the strip of spring brass F
in place against the wooden block. G is a leather strap fastened
to the weight B and the spring F connected to the latter by a
small sink bolt.

[Illustration: Electric Fire Alarm]

At the house an electric bell is placed wherever convenient.
Several battery cells, of course, are also needed. Dry batteries
are most convenient. The battery cells and bell are connected in
the usual manner, and one wire from the bell and one from the
battery are strung to the barn and connected to the binding posts
D D.

If a fire occurs in the hay-mow the blaze will generally shoot
toward the gable soon after it starts, and will then burn the
string C, which allows the weight B to fall and pull the brass
spring against the iron piece E, which closes the circuit and
rings the bell in the house.

If desired, the string may be stretched back and forth under the
roof several times or drawn through any place that is in danger of
--Contributed by Geo. B. Wrenn, Ashland, Ohio.

** How to Make a Small Electric Furnace [48]

Take a block of wood and shape into a core. One like a loaf of
bread, and about that size, serves admirably. Wrap a layer of
asbestos around it and cover this with a thin layer of
plaster-of-paris. When the plaster is nearly dry wind a coil of
No. 36 wire around it, taking care that the wire does not touch
itself anywhere. Put another course of plaster-of-paris on this,
and again wind the wire around it. Continue the process of
alternate layers of plaster and wire until 500 ft. or more of the
latter has been used, leaving about 10 in. at each end for
terminals. Then set the whole core away to dry.

For a base use a pine board 10 in. by 12 in. by 1 in. Bore four
holes at one end for binding-posts, as indicated by E E. Connect
the holes in pairs by ordinary house fuse wire. At one side secure
two receptacles, B B, and one single post switch, C. Place another
switch at I and another binding-post at F. The oven is now ready
to be connected.

Withdraw the wooden core from the coils of wire and secure the
latter by bands of tin to the board. Connect the ends of the wire
to binding-posts E and F, as shown. From the other set of
binding-posts, E, run a No. 12 or No. 14 wire, connecting lamp
receptacles, B B, and switch, C, in parallel. Connect these three
to switch, D, in series with binding-post, F, the terminal of the
coil. Place 16-cp. lights in the receptacles and connect the fuses
with a 110-volt lighting circuit. The apparatus is now ready for
operation. Turn on switch, D, and the lamps, while C is open. The
coil will commence to become warm, soon drying out the
plaster-of-paris. To obtain more heat

[Illustration: Electric Furnace]

open one lamp, and to obtain still more open the other and close
switch C.
--Contributed by Eugene Tuttles, Jr., Newark, Ohio.

** How to Make an Ammeter [49]

Every amateur mechanic who performs electrical experiments will
find use for an ammeter, and for the benefit of those who wish to
construct such an instrument the following description is given:
The operative principle

[Illustration: Complete Ammeter and Details]

of this instrument is the same as that of a galvanometer, except
that its working position is not confined to the magnetic
meridian. This is accomplished by making the needle revolve in a
vertical instead of a horizontal plane. The only adjustment
necessary is that of leveling, which is accomplished by turning
the thumbscrew shown at A, Fig. 1, until the hand points to zero
on the scale.

First make a support, Fig. 2, by bending a piece of sheet brass to
the shape indicated and tapping for the screws CC. These should
have hollow ends, as shown, for the purpose of receiving the
pivoted axle which supports the hand. The core, Fig. 3, is made of
iron. It is 1 in. long, 1/4 in. wide and 1/8 in. thick. At a point
a little above the center, drill a hole as shown at H, and through
this hole drive a piece of knitting-needle about 1/2 in. long, or
long enough to reach between the two screws shown in Fig. 2. The
ends of this small axle should be ground pointed and should turn
easily in the cavities, as the sensitiveness of the instrument
depends on the ease with which this axle turns.

After assembling the core as shown in Fig. 4, it should be filed a
little at one end until it assumes the position indicated. The
pointer or hand, Fig. 5, is made of wire, aluminum being
preferable for this purpose, although copper or steel will do.
Make the wire 4-1/2 in. long and make a loop, D, 1/2 in. from the
lower end. Solder to the short end a piece of brass, E, of such
weight that it will exactly balance the weight of the hand. This
is slipped on the pivot, and the whole thing is again placed in
position in the support. If the pointer is correctly balanced it
should take the position shown in Fig. 1, but if it is not exactly
right a little filing will bring it near enough so that it may be
corrected by the adjusting-screw.

Next make a brass frame as shown in Fig. 6. This may be made of
wood, although brass is better, as the eddy currents set up in a
conductor surrounding a magnet tend to stop oscillation of the
magnet. (The core is magnetized when a current flows through the
instrument.) The brass frame is wound with magnet wire, the size
depending on the number of amperes to be measured. Mine is wound
with two layers of No. 14 wire, 10 turns to each layer, and is
about right for ordinary experimental purposes. The ends of the
wire are fastened to the binding posts B and C, Fig. 1.

A wooden box, D, is then made and provided with a glass front. A
piece of paper is pasted on a piece of wood, which is then
fastened in the box in such a position that the hand or pointer
will lie close to the paper scale. The box is 5-1/2 in. high, 4
in. wide and 1-3/4 in. deep, inside measurements. After everything
is assembled put a drop of solder on the loop at D, Fig. 5, to
prevent it turning on the axle.

To calibrate the instrument connect as shown in Fig. 7, where A is
the homemade ammeter; B, a standard ammeter; C, a variable
resistance, and D, a battery, consisting of three or more cells
connected in multiple. Throw in enough resistance to make the
standard instrument read 1 ohm [sic: ampere] and then put a mark
on the paper scale of the instrument to be calibrated. Continue in
this way with 2 amperes, 3 amperes, 4 amperes, etc., until the
scale is full. To make a voltmeter out of this instrument, wind
with plenty of No. 36 magnet wire instead of No. 14, or if it is
desired to make an instrument for measuring both volts and
amperes, use both windings and connect to two pairs of binding
--Contributed by J.E. Dussault, Montreal.

** How to Make a Three-Way Cock for Small Model-Work [50]

[Illustration: Three-way Valve]

In making models of machines it is often necessary to contrive
some method for a 3- or 4-way valve or cock. To make one, secure a
pet cock and drill and tap hole through, as shown in the cut. If
for 3-way, drill in only to the opening already through, but if
for a 4-way, drill through the entire case and valve. Be sure to
have valve B turned so as to drill at right angles to the opening
through it. After drilling, remove the valve, take off the burr
with a piece of emery paper and replace ready for work.

** Easy Experiments with Electric-Light Circuit [50]

An electric-light circuit will be found much less expensive than
batteries for performing electrical experiments. The sketch shows
how a small arc light and motor may be connected to the light
socket, A. The light is removed and a plug with wire connections
is put in its place. One wire runs to the switch, B, and the other
connects with the water rheostat, which is used for reducing the

[Illustration: Arc-Light Motor and Water Rheostat]

A tin can, C is filled nearly to the top with salt water, and a
metal rod, D, is passed through a piece of wood fastened at the
top of the can. When the metal rod is lowered the current
increases, and as it is withdrawn the current grows weaker. In
this way the desired amount of current can be obtained.

By connecting the motor, E, and the arc light, F, as shown, either
one may be operated by turning switch B to the corresponding
point. The arc light is easily made by fastening two electric
light carbons in a wooden frame like that shown. To start the
light, turn the current on strong and bring the points of the
carbons together; then separate slightly by twisting the upper
carbon and at the same time drawing it through the hole.

** How to Make an Interrupter [51]

The Wenult interrupter is an instrument much used on large coils
and is far more efficient than the usual

[Illustration: Details of Interrupter]

form of vibrators. It can also be used with success on small coils
as well as large. Although it is a costly instrument to purchase,
it can be made with practically no expense and the construction is
very simple.

First procure a wide-mouthed bottle about 4 in. high, provided
with a rubber stopper. This stopper should be pierced, making two
holes about 1/4 in. in diameter. From a sheet of lead 1/16 in. in

[Illustration: The Completed Instrument]

cut a piece shaped like A, Fig. 1. Common tea lead folded several
times will serve the purpose. When in the bottle this lead should
be of such a size that it will only reach half way around, as
shown in B. To insert the lead plate, roll it up so it will pass
through the neck of the bottle, then smooth it out with a small
stick until it fits against the side, leaving the small strip at
the top projecting through the neck of the bottle. Bend this strip
to one side and fit in the stopper, as shown in C. A small
binding-post is fastened at the end of the strip.

Having fixed the lead plate in position, next get a piece of glass
tube having a bore of about 1/32 of an inch in diameter. A piece
of an old thermometer tube will serve this purpose. Insert this
tube in the hole in the stopper farthest from the lead plate. Get
a piece of wire that will fit the tube and about 6 in. long, and
fasten a small binding-post on one end and stick the other into
the tube. This wire should fit the hole in the tube so it can be
easily moved. In the hole nearest the lead plate insert a small
glass funnel.

The interrupter as it is when complete is shown at D, Fig. 1.
Having finished the interrupter, connect it with the
electric-light circuit as shown in Fig. 2. Fill the bottle with
water to about the line as shown in D, Fig. 1. Adjust the wire in
the small glass tube so that it projects about 1/8 in. Add
sulphuric acid until the water level rises about 1/16 in. Turn on
the current and press the button, B. If all adjustments are
correct, there will be a loud crackling noise from the
interrupter, a violet flame will appear at the end of the wire and
a hot spark will pass between the secondary terminals. If the
interrupter does not work at first, add more sulphuric acid
through the funnel and press the wire down a little more into the
liquid. A piece of wood, A, Fig. 2, should be inserted in vibrator
to prevent it from working.
--Contributed by Harold L. Jones, Carthage, N. Y.

** A Miniature "Pepper's Ghost" Illusion [52]

Probably many readers have seen a "Pepper's Ghost" illusion at
some amusement place. As there shown, the audience is generally
seated in a dark room at the end of which there is a stage with
black hangings. One of the audience is invited onto the stage,
where he is placed in an upright open

[Illustration: Pepper's Ghost]

coffin. A white shroud is thrown over his body, and his clothes
and flesh gradually fade away till nothing but his skeleton
remains, which immediately begins to dance a horrible rattling
jig. The skeleton then fades away and the man is restored again.

A simple explanation is given in the Model Engineer. Between the
audience and the coffin is a sheet of transparent glass, inclined
at an angle so as to reflect objects located behind the scenes,
but so clear as to be invisible to the audience and the man in the
coffin. At the beginning the stage is lighted only from behind the
glass. Hence the coffin and its occupant are seen through the
glass very plainly. The lights in front of the glass (behind the
scenes) are now raised very gradually as those behind the glass
are turned down, until it is dark there. The perfectly black
surface behind the glass now acts like the silver backing for a
mirror, and the object upon which the light is now turned--in this
case the skeleton--is reflected in the glass, appearing to the
audience as if really occupying the stage.

The model, which requires no special skill except that of
carpentry, is constructed as shown in the drawings.

The box containing the stage should be 14 in. by 7 in. by 7-1/2
in., inside dimensions. The box need not be made of particularly
good wood, as the entire interior, with the exception of the
glass, figures and lights, should be colored a dull black. This
can well be done by painting with a solution of lampblack in
turpentine. If everything is not black, especially the joints and
background near A, the illusion will be spoiled.

The glass should be the clearest possible, and must be thoroughly
cleansed. Its edges should nowhere be visible, and it should be
free from scratches and imperfections. The figure A should be a
doll about 4 in. high, dressed in brilliant, light-colored
garments. The skeleton is made of papier mache, and can be bought
at Japanese stores. It should preferably be one with arms
suspended by small spiral springs, giving a limp, loose-jointed
effect. The method of causing the skeleton to dance is shown in
the front view. The figure is hung from the neck by a blackened
stiff wire attached to the hammer wire of an electric bell, from
which the gong has been removed. When the bell works he will kick
against the rear wall, and wave his arms up and down, thus giving
as realistic a dance as anyone, could expect from a skeleton.

The lights, L and M, should be miniature electric lamps, which can
be run by three dry cells. They need to give a fairly strong
light, especially L, which should have a conical tin reflector to
increase its brilliancy and prevent its being reflected in the

Since the stage should be some distance from the audience, to aid
the illusion, the angle of the glass and the inclination of the
doll, A, has been so designed that if the stage is placed on a
mantle or other high shelf, the image of A will appear upright to
an observer sitting in a chair some distance away, within the
limits of an ordinary room. If it is desired to place the box
lower down, other angles for the image and glass may be found
necessary, but the proper tilt can be found readily by experiment.

The electric connections are so simple that they are not shown in
the drawings. All that is necessary is a two-point switch, by
which either L or M can be placed in circuit with the battery, and
a press button in circuit with the bell and its cell.

If a gradual transformation is desired, a double-pointed rheostat
could be used, so that as one light dims the other increases in
brilliancy, by the insertion and removal of resistance coils.

With a clear glass and a dark room this model has proved to be
fully as bewildering as its prototype.

** Experiment with Colored Electric Lamps [53]

To many the following experiment may be much more easily performed
than explained: Place the hand or other object in the light coming
from two incandescent lamps, one red and

[Illustration: Two-Colored Hand]

one white, placed about a foot apart, and allow the shadow to fall
on a white screen such as a table-cloth. Portions of the shadow
will then appear to be a bright green. A similar experiment
consists in first turning on the red light for about a minute and
then turning it off at the same time that the white one is turned
on. The entire screen will then appear to be a vivid green for
about one second, after which it assumes its normal color.

** To Explode Powder with Electricity [53]

A 1-in. hole was bored in the center of a 2-in. square block. Two
finishing nails were driven in, as shown in the sketch. These were
connected to terminals of an induction coil. After everything was
ready the powder was poured in the hole and a board weighted with
rocks placed over the block. When the button is pressed

[Illustration: Exploding Powder]

or the circuit closed in some other way the discharge occurs. The
distance between the nail points--which must be bright and
clean--should be just enough to give a good, fat spark.
--Contributed by Geo. W. Fry, San Jose, Cal.

** Simple Wireless System [54]

The illustrations will make plain a simple and inexpensive
apparatus for

[Illustration: Simple Wireless System]

wireless telegraphy by which I have had no difficulty in sending
messages across 1-1/2 miles of water surface. It is so simple that
the cuts scarcely need explanation. In Fig. 1 is seen the sending
apparatus, consisting of a 40-cell battery connected with two
copper plates 36 by 36 by 1/8 in. The plates are separated 6 in.
by a piece of hard rubber at each end.

In Fig. 2 are seen duplicates of these insulated plates, connected
with an ordinary telephone receiver. With this receiver I can hear
distinctly the electric signals made by closing and opening the
Morse key in Fig. 1, and I believe that in a short time I shall be
able to perfect this system so as to send wireless messages over
long distances.
--Contributed by Dudley H. Cohen, New York.

** Stop Crawling Water Colors [54]

To prevent water colors from crawling, add a few drops of ammonia
or lime water, or a solution of sal soda.

** Small Electrical Hydrogen Generator [54]

A small hydrogen generator may be made from a fruit jar, A (see
sketch), with two tubes, B and C, soldered in the top. The plates
E can be made of tin or galvanized iron, and should be separated
about 1/8 in. by small pieces of wood. One of these plates is
connected to metal top, and the wire from the other passes through
the tube B, which is filled with melted rosin or wax, to make it
airtight. This wire connects to one side of a battery of two
cells, the other wire being soldered to the metal top of the jar,
as shown. The jar is partly filled with a very dilute solution of
sulphuric acid, about 1 part of acid to 20 of water.

When the current of electricity passes between the plates E,
hydrogen gas is generated, which rises and passes through the
rubber hose D, into the receiver G. This is a wide-mouth bottle,
which is filled with water and inverted over a pan of water, F.

[Illustration: Hydrogen Generator]

The gas bubbling up displaces the water and fills the bottle.

If the receiver is removed when half full of gas, the remaining
space will be filled with air, which will mix with the gas and
form an explosive mixture. If a lighted match is then held near
the mouth of the bottle a sharp report will be heard.

If the bottle is fitted with a cork containing two wires nearly
touching, and the apparatus connected with an induction coil, in
such a manner that a spark will be produced inside the bottle, the
explosion will blowout the cork or possibly break the bottle.
Caution should be used to avoid being struck by pieces of flying
glass if this experiment is tried, and under no condition should a
lighted match or spark be brought near the end of the rubber hose
D, as the presence of a little air in the generator will make an
explosive mixture which would probably break the jar.

** Gasoline Burner for Model Work [55]

When making a small model traction engine or a locomotive the
question arises, "What shall the fuel be?" If you have decided to
use gasoline, then a suitable burner is necessary. A piece of
brass tubing about 3 in. in diameter and 6 in. long with caps
screwed on both ends and fitted with a filling plug and a bicycle
valve makes a good gasoline supply tank, says the Model Engineer,
London. The bicycle valve is used to give the tank an air pressure
which forces the gasoline to the burner.

The burner is made from a piece of brass tube, A, as is shown in
the illustration, 1/2 in. in diameter and 2-1/2 in. long, which is
plugged up at both ends, one end being drilled and reamed out to
5/16 in. Three rows of holes 1/16 in. in diameter are drilled in
the brass tube. One row is drilled to come directly on top, and
the other two at about 45 degrees from the vertical. It is then
fitted to a sheet steel base, B, by means of the clips, C C, Fig.
1. A piece of 1/8-in. copper pipe, P, is then coiled around the
brass tube, A, which forms the vaporizing coil. This coil should
have a diameter

[Illustration: Gasoline Burner]

of only 1 in. One end of the copper tube is bent around so it will
point directly into the reamed-out hole in the end of the brass
tube, A. A nipple, N, is made by drilling a 1/8-in. hole halfway
through a piece of brass and tapping to screw on the end of the
1/8-in. copper pipe. A 1/64-in. hole is then drilled through the
remaining part of the nipple. The other end of the copper tube is
connected to the supply tank. The distance between the nipple, N,
and the ends of the tube, A, should be only 5/16 of an inch. Fig.
2 shows the end view.

** A Homemade Telephone Receiver [55]

A telephone receiver that will do good work may be built very
cheaply as follows: For the case use an ordinary 1/2-lb.
baking-powder box with a piece of heavy wire soldered on the
inside, 1-5/16 in. from the bottom. For the magnet use a piece of
round hardened steel about 3/8 in. in diameter and 1-1/4 in. long.
If desired, a piece of an old round file may be used for the
magnet core, which should be magnetized previous to assembling,
either by passing a current of electricity around it, or by direct
contact with another magnet. The steel core should be wound with
about 250 ft. of No. 36 insulated wire, the ends of which should
be soldered to a piece of

[Illustration: Telephone Receiver]

lamp cord, passed through a hole in the bottom of the can and
knotted inside to prevent pulling out.

A disk of thin sheet-iron, such as is used by photographers for
tintypes (Ferrotype), should be cut to the diameter of the can,
taking care not to bend the iron. The magnet should then be placed
in the bottom of the can in an upright position and enough of a
melted mixture of beeswax and resin poured in to hold it in

While the wax is still in a plastic condition the magnet should be
located centrally and adjusted so that the end will be 1/16 in. or
less below the level of the top of the copper ring.

After the wax has hardened the disk is slipped in and fastened
tightly by a ring of solder when the instrument is ready for use.

** How to Bind Magazines [56]

An easy way to bind Popular Mechanics in volumes of six months
each is to arrange the magazines in order and tie them securely
both ways with a strong cord. It is well to put two or three
sheets of tough white paper, cut to the size of the pages, at the
front and back for fly leaves.

Clamp the whole in a vise or clamp with two strips of wood even
with the back edges of the magazines. With a sharp saw cut a slit
in the magazines and wood strips about 1/2 in. deep and slanting
as shown at A and B, Fig. 1. Take two strips of stout cloth, about
8 or 10 in. long and as wide as the distance between the bottoms
of the sawed slits. Lay these over the back edge of the pack and
tie securely through the slits with a string thread--wrapping and
tying several times (C, Fig. 2).

If you have access to a printer's paper knife, trim both ends and
the front edge; this makes a much nicer book, but if the paper
knife cannot be used, clamp the whole between two boards and saw
off the edges, boards and all, smoothly, with a fine saw.

Cut four pieces of cardboard, 1/4 in. longer and 1/4 in. narrower
than the magazines after they have been trimmed. Lay one piece of
the board on the book and under the cloth strips. Use ordinary
flour paste and paste the strips to the cardboard and then rub
paste all over the top of the strips and the board. Rub paste over
one side of another piece of board and put it on top of the first
board and strips, pressing down firmly so that the strips are held
securely between the two boards. Turn the book over and do the
same with the other two boards.

After the paste has dried a few minutes take a piece of strong
cloth, duck or linen, fold and cut it 1 in. larger all around than
the book, leaving the folded edge uncut. Rub paste over one of the
board backs and lay one end of the cloth on it, smoothing and
creasing as shown at A, Fig. 3. Turn the book over and paste the
other side. The back edges should have a good coat of paste and a
strip of paper

[Illustration: Process of Homemade Binding]

the width of the thickness of the pack pasted on before pasting
the cloth to the second board back.

Cut off the corners and fold over the edges of the cloth, pasting
them down (Fig. 4). Rub paste on one side of a fly leaf and press
the back down on it. Turn the book over and paste a fly leaf to
the other back after the edges of the cloth have been folded down.
The backs must not be opened until the fly leaves are thoroughly
dry. Trim and tuck in the ends of the strip at the back edge.

When fixed this way your magazines make one of the most valuable
volumes you can possibly add to your library of mechanical books.
--Contributed by Joseph N. Parker, Bedford City, Va.

** A Homemade Acetylene-Gas Generator [57]

A simple acetylene-gas generator used by myself for several years

[Illustration: Acetylene Gas Generator]

out on camping trips was made of a galvanized iron tank, without a
head, 18 in. in diameter and 30 in. deep, B, as shown in the
sketch. Another tank, A, is made the same depth as B, but its
diameter is a little smaller, so that inverted it will just slip
easily into the tank B. In the bottom, or rather the top now, of
tank A is cut a hole, and a little can, D, is fitted in it and
soldered. On top and over can D is soldered a large tin can screw.
A rubber washer is fitted on this so that when the screw top, E,
is turned on it, the joint will be gas tight. Another can, C,
which will just slip inside the little can, is perforated with a
number of holes. This can C is filled about half full of broken
pieces of carbide and then placed in the little can D. A gas cock,
H, is soldered onto tank A, as shown, from which the gas may be
taken through a rubber tube. Fill tank B with water and set tank A
into it. This will cause some air to be enclosed, which can be
released by leaving the cock open until tank A settles down to the
point where the water will begin to run in the perforations of the
little tank. The water then comes in contact with the carbide and
forms gas, which expands and stops the lowering of tank A. Then
the cock must be closed and tubing attached. It is dangerous to
attempt to strike a match to light a jet or the end of the cock
while air is escaping and just as the first gas is being made.
Wait until the tank is well raised up before doing this.
--Contributed by James E. Noble, Toronto, Ont.

** Homemade Annunciator [57]

When one electric bell is operated from two push-buttons it is
impossible to tell which of the two push-buttons is being operated
unless an annunciator or similar device is used. A very simple
annunciator for indicating two numbers can be made from a small
box, Fig. 1, with an electric-bell magnet, A, fastened in the
bottom. The armature, B, is pivoted in the center by means of a
small piece of wire and has an indicator or hand, C, which moves
to either right or left, depending on which half of the magnet is
magnetized. If the back armature, D, of the magnet is removed the
moving armature will work better, as this will prevent the
magnetism from acting on both ends of the armature.

The wiring diagram, Fig. 2, shows how the connections are to be
made. If the pushbutton A is closed; the bell will ring and the
pointer will point at 1,

[Illustration: Annuciator and Wiring Diagram]

while the closing of the push-button B will ring the bell and move
the pointer to 2.
--Contributed by H. S. Bott, Beverly, N. J.

** How to Make a Box Kite [58]

As some of the readers of Amateur Mechanics may desire to build a
box kite, a simple method of constructing one of the modern type
is given in detail as follows: The sticks should be made of
straight grained wood, which may be either spruce, basswood or
white pine. The longitudinal corner spines, A A, should be 3/8 in.
square by 42 in. long, and the four diagonal struts, B, should be
1/4 in. by 1/2 in., and about 26 in. long. Two cloth bands should
be made to the exact dimensions given in the sketch and fastened
to the four longitudinal sticks with 1 oz. tacks. It is well to
mark the positions of the sticks on the cloth bands, either with a
soft lead-pencil or crayon, in order to have the four sides of
each band exactly equal. The ends of the bands should be lapped
over at least 1/2 in. and sewed double to give extra strength, and
the edges should be carefully hemmed, making the width, when
finished, exactly 12 in. Probably the best cloth for this purpose
is nainsook, although lonsdale cambric or lightweight percaline
will answer nearly as well.

The diagonal struts, B, should be cut a little too long, so that
they will be slightly bowed when put in position, thus holding the
cloth out taut and flat. They should be tied together at the
points of intersection and the ends should be wound with coarse
harness maker's thread, as shown at C, to prevent splitting. The
small guards, D, are nailed or glued to the longitudinal sticks to
prevent the struts slipping out of position. Of course the ends of
the struts could be fastened to the longitudinal strips if
desired, but if made as described the kite may be readily taken
apart and rolled up for convenience in carrying.

The bridle knots, E, are shown in detail at H and J. H is a square
knot, which may be easily loosened and

[Illustration: Detail of Box Kite]

shifted to a different position on the bridle, thus adjusting the
lengths of F and G. A bowline knot should be tied at J, as shown,
to prevent slipping. If the kite is used in a light wind, loosen
the square knot and shift nearer to G, thus shortening G and
lengthening F, and if a strong wind is blowing, shift toward F,
thereby lengthening G and making F shorter. In a very strong wind
do not use the bridle, but fasten a string securely to the stick
at K.
--Contributed by Edw. E. Harbert, Chicago.

** Lubricating a Camera Shutter [58]

An experienced photographer uses blacklead [graphite] for grooves
about a camera or holder. A small quantity is rubbed well into the
grooves and on the edges of shutters, that refuse to slide easily,
with gratifying results. Care must be taken to allow no dust to
settle in the holders, however.

** Simple Open-Circuit Telegraph Line [59]

By using the circuit shown in the sketch for short-distance
telegraph lines, the extra switches and wiring found in many
circuits are done away with. Closing either key will operate both
sounders, and, as the resistance of

[Illustration: Simple Telegraph Line]

the sounders is very high, the batteries do not run down for a
long time.
--Contributed by A. D. Stoddard, Clay Center, Kan.

** How to Make a Thermo Battery [59]

A thermo battery, for producing electricity direct from heat, can
be made of a wooden frame, A, with a number of nails, B, driven in
the vertical piece and connected in series with heavy copper
wires, C. The connections should all be soldered to give good
results, as the voltage is

[Illustration: Thermo Battery]

very low and the resistance of an unsoldered joint would stop the
current. The heat may be supplied by an alcohol lamp or other
device, and the current may then be detected by means, of a simple
galvanometer consisting of a square spool of No. 14 or No. 16
single-covered wire, E, with a pocket compass, F, placed on top.
Turn the spool in a north and south direction, or parallel with
the compass needle. Then, when the nail heads are heated and the
circuit completed, the needle will swing around it at right angles
to the coils of wire. Applying ice or cold water to the nail heads
will reverse the current.
--Contributed by A. C. A., Chicago.

** How to Discharge a Toy Cannon by Electricity [59]

A device for discharging a toy cannon by electricity can be easily
made by using three or four dry batteries, a switch and a small
induction coil

[Illustration: Electrical Attachment for Discharging Toy Cannon]

capable of giving a 1/8-in. spark. Fasten a piece of wood, A, to
the cannon, by means of machine screws or, if there are no
trunnions on the cannon, the wood may be made in the shape of a
ring and slipped on over the muzzle. The fuse hole of the cannon
is counterbored as shown and a small hole is drilled at one side
to receive a small piece of copper wire, E. The wood screw, C,
nearly touches E and is connected to one binding post of the
induction coil. The other binding post is connected with the wood
screw, D, which conducts the current into the cannon, and also
holds the pieces of wood, A and B, in position.

When the cannon is loaded, a small quantity of powder is placed in
the counterbore, and the spark between C and E ignites this and
discharges the cannon. A cannon may be fired from a distance in
this way, and as there is no danger of any spark remaining after
the current is shut off, it is safer than the ordinary cannon
which is fired by means of a fuse.
--Contributed by Henry Peck, Big Rapids, Mich.

** Simple Electric Lock [60]

The illustration shows an automatic lock operated by electricity,
requiring a strong magnet, but no weights or strings, which
greatly simplifies the device over many others of the kind.

[Illustration: Lock Operated by a Magnet]

The weight of the long arm, L, is just a trifle greater than the
combined weights of the short arms, A and S. The fulcrum of the
lever is at C, where there is a staple. The lever swings on one
arm of the staple and the other arm is so placed that when the
lever is in an upright position, with the long arm at L', it will
not fall because of its greater weight but stays in the position
shown. The purpose of this is to leave the short arm, A, when in
position at A', within the reach of the magnet. Arm L rests on an
L-shaped hook, H; in this position the door is locked.

To unlock the door, press the button, B. The momentum acquired
from the magnet by the short arms, A and S, is sufficient to move
the long arm up to the position of L'. To lock the door, press the
button and the momentum acquired from the magnet by the short
arms, now at A' and S', is sufficient to move the long arm down
from L' to the position at L.
--Contributed by Benjamin Kubelsky, Chicago.

** Direct-Connected Reverse for Small Motors [60]

A simple reverse for small motors can be attached directly to the
motor as shown in Fig. 1. Fig. 2 shows the construction of the
reverse block: A is a strip of walnut 5/8 in. square and 3/8 in.
thick with strips of brass or copper (BB) attached as shown. Holes
(CC) are drilled for the wire connections and they must be flush
with the surface of the block. A hole for a 1/2 in. screw is bored
in the block. In Fig. 1, D is a thin strip of walnut or other
dense, hard wood fitted to the binding posts of the brush holders,
to receive the screw in the center.

Before putting the reverse block on the motor, remove all the
connections between the lower binding posts and the brush holders
and connect both ends of the field coil to the lower posts. Bend
the strips BB (Fig. 2) to the proper position to make a wiping
contact with the nuts holding the strip of wood D, Fig. 1. Put the
screw in tight

[Illustration: Direct-Connected Reverse]

enough to make the block turn a little hard. Connect as shown in
the illustration. To reverse, turn the block so the strips change
connections and the motor will do the rest.
--Contributed by Joseph B. Keil, Marion, Ohio.

** A Handy Ice Chisel [61]

Fishing through the ice is great sport, but cutting the first
holes preparatory to setting the lines is not always an easy task.
The ice chisel here described will be found very handy, and may be
made at very slight expense.

In the top of an old ax-head drill a 9/16-in. hole, and then tap
it for a 3/8-in. gas-pipe, about 18 in. long. Thread the other end
of the pipe, and screw on

[Illustration: Combination Ax and Ice Chisel]

an old snow-shovel handle. When ready for use, screw the two
pieces together and you have your chisel complete.

A short ax-handle may be included in the outfit. When the holes
are finished and your lines set, unscrew the pipe from the head of
the ax, put in the handle, and your ax is ready to cut the wood to
keep your fire going.
--Contributed by C. J. Rand, West Somerville, Mass.

** More Uses for Pipe Fittings [61]

It would seem that the number of useful articles that can be made
from pipes and fittings is unlimited. The sketch shows two more
that may be added to the list. A and B are front and side views of
a lamp-screen, and C is a dumbbell. The lamp shade is particularly
useful for shading the eyes when reading or writing and, if
enameled white on the concave side, makes an excellent reflector
for drawing at night, or for microscopic work.

The standard and base, consisting of an ordinary pipe flange
bushed down to receive the upright nipple, are enameled a jet
black, and if the device is to be used on a polished table, a
piece of

[Illustration: Lamp Shade and Dumbbell]

felt should be glued to the bottom. A good way to hold the fan in
the nipple is to use a small wedge.

The dumbbells are made of short pieces of 3/4-in. pipe with
1-2-in. couplings fastened to each end by pouring melted lead in
the space between the pipes and the couplings. The appearance is
greatly improved by enameling black, and if desired the handles
may be covered with leather.
--Contributed by C. E. Warren, M. D., North Easton, Mass.

** Sealing-Wax Bent While Cold [61]

If a piece of sealing-wax is supported in a horizontal position by
one end, as shown at A in the sketch, it will gradually bend to
the shape indicated by the dotted lines B. To attempt bending it
with the hands would result in breaking it unless a steady
pressure were applied for a long time. This peculiar property is
also found in ice.

[Illustration: Bending Cold Sealing-Wax]

** Homemade Pottery Kiln [62]

A small kiln for baking clay figures may be built at a cost of $1.
The following shows the general plan of such a kiln which has
stood the test of 200 firings, and which is good for any work
requiring less than 1400 deg. C.

Get an iron pail about 1 ft. high by 1 ft. across, with a cover.
Any old pail which is thick enough will do, while a new one will
cost about 80 cents. In the bottom of this cut a 2-in. round hole
and close it with a cork or wood plug, A, Fig. 1, which shall
project at least 2 in. inside the pail. Make a cylindrical core of
wood, B, Fig. 1, 8 in. long and 8 in. across. Make a

[Illustration: Homemade Pottery Kiln]

mixture of clay, 60%; sand, 15%; and graphite, 25%, kneading
thoroughly in water to a good molding consistency. Line the pail,
bottom and sides, with heavy paper and cover the core with same.
Now pack the bottom of the pail thoroughly with a 2-in. layer of
the clay mixture, and on it set the paper wrapped core, carefully
centering it. The 2 in. of space between the core and the sides of
the pail all around is to be filled with clay, C, as is shown in
the sketch, using a little at a time and packing it very tight. In
like manner make the cover of the kiln, cutting the hole a little
smaller, about 1 in. At the edge or rim of the cover encircle a
2-in. strip of sheet iron, E, Fig. 2, to hold the clay mixture, C.
Set aside for a few days until well dried.

While these are drying you may be making a muffle, if there is to
be any glazing done. This is a clay cylinder (Fig. 3) with false
top and bottom, in which the pottery to be glazed is protected
from any smoke or dust. It is placed inside the kiln, setting on

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