138
��Popular Science Monthly
��A Keyless Collapsible Letter Box for Army Camps
THE letter box shown below was origi- nated by a mechanic in the Field Artillery of the U. S. Army. The upper part of the box consists of a wood frame to admit the upper part of
Flail slotx Tin cover
��Wooden frame
���Letter box designed especially for use in the army camp. It is portable
a canvas bag. It is so constructed that when the metal cover is raised the canvas bag is released. Only army officers who are authorized to do so make the collections. The whole device can be readily taken down and packed for shipment. — Dudley Hess.
��state and then add enough water to make a stifif paste. Apply it to the stove lining where the repairs are required. The car- borundum in this mixture helps the lining to withstand the heat, since carborundum is an artificial substance, made under intense heat in an electric furnace.
After the lining is applied to the stove, let it dry for several days, if possible. When starting a fire for the first time, let the fire come to its maximum heat gradually. After that, any kind of firing may be done, as the lining, once having thoroughly dried, will keep in good condition for an indefinite time. — W. S. Standiford.
��How to Make a Good Lining for Stove Fireplaces
IRON fireboxes, whether made of cast or wrought iron, usually deteriorate when the fires are kept constantly going for any length of time. To prevent this, the stove manufacturers supply their stoves with fire- places having firebrick linings. Even these in time, due to the action of the heat, break into pieces, thus exposing the iron to the action of the heat. The following cement will take the place of the brick satisfactorily and it withstands heat. Take 6 parts of potters clay, 2 parts of plaster of Paris or cement if obtainable, 1 part of wood ashes, and 3 parts of carborundum in powder form. Mix all of the ingredients in the dry
��Homemade Copying Paper for Manifold Work
HOMEMADE copying paper, pre- pared by rubbing one side of com- mon scratch paper with a very soft lead pencil, is more satisfactory for many pur- poses than carbon paper. For transferring map lines from field sheets to the office map, copying drawings, sketches, etc., it will be found very convenient.
Lines traced on a map or drawing made from such copying paper can be very easily erased. The erasure of the usual carbon-paper lines is not so readily accomplished. — Peter J. M. Clute.
��Blowing a Pocket Gear From an Automobile Transmission
A POCKET gear on an automobile transmission having a thrust button, became cracked and it was necessary to
remove it. The crack caused a burr in the hole that prevented the removal of the gear. The only method that could be used was the usual one of explod- ing powder back of the pinion stud. A small hole was drilled in the shaft to gain entrance to the space back of this stud and into this a quantity of powder was poured. The powder was ignited with a fuse and the pinion removed. — Geo. F. Weiher.
���Holding part in vise for blowing out the pinion
�� �
