158 



HORTICULTURIST S RULE-BOOK. 



The preceding table gives tlie standard sizes and principal 

 dimensions of wrought-iron pipe. From tliis table the amount 

 required for a given amount of radiating surface can be readily 

 computed. This pipe can be purchased of any dealer. 



4. To design heating Surface. 



1st. Find radiating surface by dividing area of glass in square 

 feet by results in Table II. Hot-water pipes can be kept at a 

 temperature of 180° F. if desired. 



2d. Find the amount of pipe by dividing amount of radiat- 

 ing surface by number of feet required per square foot of 

 radiating surface, as given in Table III. Do not .use pipe less 

 than H inches in diameter for radiating surface. 



3d. Find size of main pipes by Table II., using size next 

 larger when radiating surface comes between numbers given. 

 It is usually better to have several main and retarn pipes, and 

 divide the radiating surface in sections. 



II. Various Estimates and Recipes. 

 Effects of Wind in cooling Glass, (Leuchars.) 



Time 



Velocity of "Wind 

 per hour. 



minutes. 



equired to lower Temperature 

 from 1-20 to 100 Fahr. 



6. Per Cent of Rays of Light reflected from Glass Roofs at Vari- 

 ous Angles of Divergence from the Perpendicular. (Bouguer.) 



1° 2.5 per cent. 



X0° . . . , . , 2.5 



