Testing Engines

—The economy of steam engines as usually determined, relates to the weight of water consumed, to the quantity of coal used in making the steam, or to the number of heat units supplied; while in other forms of heat engine, it relates to the amount of gas, oil, or other fuel burned, The heat consumption of internal combustion | engines is found by ascertaining the total heat of | combustion of the particular fuel used, as determined by a calorimeter test, and multiplying the result by the quantity of fuel consumed. In determining the total heat of combustion no deduction is made for the latent heat of the vapor of water in the products of combustion.