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The dairy barn, of course, is not the only building that requires ventilation. 

 Pure air is just as important in horse stables, hog houses, poultry houses, homes, 

 factories, moving picture theatres, and wherever else human beings or animals 

 may be brought together within the walls of a building. It is needed also for 

 tobacco houses, and buildings of like nature. 



To meet these varying conditions, we make James Ventilators in a variety 

 of sizes and of two general types — Solid Hood and Revolving Hood. 



The James Ventilator with the solid hood is just as efficient as any ven- 

 tilator other than the James now on the market for use on dairy barns; indeed, 

 it is more efficient than most of them. 



The most efficient type, of course, is the James Ventilator with the revolv- 

 ing hood, because it offers the least resistance to the outflow of foul air, provides 

 greater capacity at the outlet openings, and because it takes advantage of the 

 suction power of the wind to exert a pull on the foul air in the outtake flue. 



Actual tests by a competent engineer have shown that the James Ventilator 

 with revolving hood gives 65 per cent better ventilation than the usual wooden 

 cupola and 30 per cent better ventilation than the ordinary ventilator for dairy 

 barns. 



This great superiority of the James Revolving Hood Ventilator is due to 

 these three James principles: (I) construction that offers the least possible 

 hindrance to the outward flow of foul air; (2) increasing the outlet space for 

 outflowing air, by addition of outlet space provided by revolving head; (3) the 

 application of suction at the proper point to help pull the foul air out. 



How these three important principles are combined with the best features 

 of other types of ventilators, at the same time avoiding their disadvantages, 

 can perhaps best be shown by a brief discussion of the principles on which 

 ventilators are constructed, and the reasons why certain features are essential. 



A ventilating flue is much like a chimney. But while the same principles 

 apply to both, with a ventilating flue it is necessary to go a step or two further. 



A ventilating flue, like a chimney, should be as straight as practicable, 

 higher than the building, of ample size; and airtight to "draw well." 



How Ventilating Flue Differs from Chimney 



The ventilating flue, however, cannot be left without a cap, as may oft- 

 times be done with a chimney, and a little thought will make the reason clear. 



Rain and snow falling into the chimney do no harm, for the heat is suffi- 

 cient to vaporize the moisture and the upward current carries it out again. 



With a ventilating flue, however, there is not sufficient heat for this pur- 

 pose, and hence, even were there no other reason, a ventilating flue would need 

 to be capped to protect against the weather. 



The foul air, in order to leave an outtake flue not capped with the right 

 type of ventilator, would often have to fight its way directly against counter 



