Doubling the diameter of a pipe increases its capacity four times.
To find the pressure in pounds per square inch of a column of water: Multiply the height of the column in feet by .434.
Standard Horse-power: The evaporation of 30 pounds of water per hour from a feed water temperature of 1,000 degrees Fahrenheit into steam at 70 pounds gauge pressure.
To find the capacity of any tank in gallons: Square the diameter in inches, multiply by the length, and then by .0034.
In making patterns for aluminum castings provision must be made for shrinkage to a greater extent than with any other metal or alloy.
The toughness of aluminum can be increased by adding a small per cent. of phosphorus.
All alloys of metals having mercury are called _amalgams_.
A sheet of zinc suspended in the water of a boiler will produce an electrolytic action and prevent scaling to a considerable extent.
Hydrofluoric acid will not affect a pure diamond, but will dissolve all imitations.
A strong solution of alum put into glue will make it insoluble in water.
A grindstone with one side harder than the other can have its flinty side softened by immersing that part in boiled linseed oil.
To find the speed of a driven pulley of a given diameter: Multiply the diameter of the driving pulley by its speed or number of revolutions. Divide this by the diameter of the driven pulley. The result will be the number of revolutions of the driven pulley.
To find the diameter of a driven pulley that shall make any given number of revolutions in the same time: Multiply the diameter of the driving pulley by its number of revolutions, and divide the product by the number of revolutions of the driven pulley.
A piece of the well-known tar soap held against the inside of a belt while running will prevent it from slipping, and will not injure the belt.
Boiler scale is composed of the carbonate or the sulphate of lime. To prevent the formation it is necessary to use some substance which will precipitate these elements in the water. The cheapest and most universally used for this purpose are soda ash and caustic soda.
Gold bronze is merely a mixture of equal parts of oxide of tin and sulphur. To unite them they are heated for some time in an earthen retort.