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.