Diameters for cylindrical chimney-flues, for given heights and boiler capacities (R. C. Carpenter)

Four-cornered chimneys are considered to be equivalent to cylindrical chimneys when the sides equal the diameter.

Effects of wind in cooling glass (Leuchars)

Table of radiation for glass (Dean 1)

1 From Dean's " Greenhouse Heating," by permission of " Domestic Engineering."

Radiating surface of pipes of different lengths and diameters

Method for finding boiler capacity for cast-iron pipe

Table showing how to get at the amount of 31/2-inch cast-iron pipe necessary to heat greenhouse to temperature wanted, when outside temperature is at zero, Fahrenheit (Lord & Burnham Co.)

For 10° below zero, add 10 per cent.; for 20° add 20 per cent., and so on. For 70° to 75° divide square feet of glass and equivalent by 1.8. For 65° to 70° divide square feet of glass and equivalent by 2.28. For 60° to 65° divide square feet of glass and equivalent by 2.62. For 55° to 60° divide square feet of glass and equivalent by 3. For 50° to 55° divide square feet of glass and equivalent by 3.46. For 45° to 50° divide square feet of glass and equivalent by 4. For 40° to 45° divide square feet of glass and equivalent by 4.67. For 35° to 40° divide square feet of glass and equivalent by 5.5.

For 2-inch work, use same table and same example and multiply the amount of 31/2-inch pipe obtained by 1.68.

In proportioning glass surface, all wall surface must be figured in; about 5 feet of wall equals 1 foot of glass.

Customary Temperatures In Which Plants Are Grown Under Glass