How to Splice a Belt in Order to Make it Run Like an Endless Belt.—Use the toughest yellow glue prepared in the ordinary way, while hot, stirring in thoroughly about 20 per cent of its weight of tannic acid, or extract of tan bark. Apply to the splice and quickly clamp together. The splice should be made of scarfed edges extending 3 to 6 inches back, according to thickness of belt. The surface to be perfectly clean and free from oil.
How Many Pounds of Coal it Requires to Maintain Steam of One-Horse Power per Hour.—Anthracite 1-1/2 to 5 pounds, according to the economy of boiler and engine. Bituminous and anthracite coal are very nearly equal for equal qualities. They both vary from 7 to 10 pounds of water evaporated per pound of coal from a temperature of 212 degrees.
A Formula for Collodio-bromide Emulsion that is Rapid.—Ether s.g. 0.720, 4 fluid ounces; alcohol s.g. 0.820, 2-1/2 fluid ounces; pyroxyline, 40 grains; castile soap dissolved in alcohol, 30 grains; bromide of ammonium and cadmium, 56 grains.
How to Deaden the Noise of Steam While Blowing off Through a Wrought Iron Stand Pipe.—The sound may be much modified by enlarging the end of the pipe like a trumpet or cone; which should be long, 20 or 30 times the diameter of the pipe, opening to 4 or 5 times its initial size.
Why Fusible Plugs are Put in the Crown Sheet of Locomotive Boilers.—To save the crown sheet from burning in case of low water, when the plug melts and lets the steam and water into the fire chamber to dampen and put out the fire as well as to make an alarm. They may also be employed on other forms of boilers, and are much used in connection with whistles for low-water alarms only. Boilers should not be blown out for cleaning with fire under them or while the walls (if set in brick) are hot enough to do damage to the iron shell. Locomotive boilers may be blown out very soon after the fire is entirely removed. All brick-set boilers should be left several hours after the fire is drawn before blowing off for cleaning.
How to Lace a Quarter Turn Belt so as to Have an Equal Strain on Both Edges of the Belt.—Begin on the outside of the belt at the middle, pass one end of the lacing through one end of the belt and bring it out through the corresponding hole of the other end of the belt, laying it diagonally off to the left. Now pass the other end of the lacing through the hole last used, and carry it over the first strand of the lacing on the inside of the belt, passing it through the first hole used, and lay it diagonally off to the right. Now proceed to pass the lacing through the holes of the belt in a zigzag course, leaving all the strands inside the belt parallel with the belt, and all the strands outside the belt oblique. Pass the lace twice through the holes nearest the edge of the belt, then return the lace in the reverse order toward the center of the belt, so as to cross all the oblique strands, and make all the inside strands double. Finally pass the end of the lacing through the first hole used, then outward through an awl hole, then hammering it down to cause it to hold. The left side is to be laced in a similar way.
A Useful Hint to Draughtsmen.—To strain drawing paper on a board, cut the paper to the size required, lay it on the board face downwards and thoroughly wet the surface with a damp sponge or brush, then turn it over and wet the face in the same way; roll it up tightly and let it stay so for five or six minutes, unroll it, and turn up the edges about an inch all around. Take liquid glue (Jackson's is the best) and apply it carefully to the edges, then turn them down, and with a paper knife press them to the board all around. Put the board in an inclined position where it is not too dry or warm, or the paper will dry too fast and tear. If it is allowed to dry slowly the surface will be perfectly even and smooth, and a pleasure to draw upon.
Joints for Hot Water Pipes.—Sal-ammoniac, 2 oz.; sublimed sulphur, 1 oz.; cast-iron filings, 1 lb. Mix in a mortar, and keep the powder dry. When it is to be used, mix it with twenty times its weight of clean iron filings, and grind the whole in a mortar. Wet with water until it becomes of convenient consistence. After a time it becomes as hard and strong as any part of the metal.
When the Process of Galvanizing Iron was First Known.—A. The process of coating iron with zinc, or zinc and tin, is a French invention, and was patented in England in 1837.
A Timber Test.—The soundness of timber may be ascertained by placing the ear close to one end of the log, while another person delivers a succession of smart blows with a hammer or mallet upon the opposite end, when a continuance of the vibrations will indicate to an experienced ear even the degree of soundness. If only a dull thud meets the ear, the listener may be certain that unsoundness exists.