No. 6. DEPARTMENT OF AGRICULTURE. 751 



"What makes the milk test vary so?" is still a burning question, 

 though less so than it used to be. I sometimes wonder whether 

 it is because dairymen understand it better, or because they are 

 hardened to it; whether more accurate sampling and testing and 

 better informed operators and superior mechanisms have lessened 

 the proportion of incorrect testing, or, whether the judicious use of 

 a lead pencil in the office "evens things up." I do not know; but 

 this I do know; that any intelligent farmer who wishes can own 

 and run a Babcock and determine the truth for himself if he is care- 

 ful and informed, but not unless he is careful and well informed. 



May market milk be lettered by aught that science has done for 

 dairying ? 



Yes, if or now are better understood than of old: 



1. The principles underlying stable ventilation and the causes of 

 its failures. 



2. The sources whence are derived the organisms which cause an- 

 noyance, loss of products or disease; also how to avoid the damage 

 they do. 



3. The dangers of "doping." 



The topic of stable ventilation is one which is often ventilated. 

 Since much animal disease is due to or its spread promoted by the 

 housing of cows in ill ventilated stables, it is a dollar and cents prop- 

 osition to try and better this condition. Too little oxygen and too 

 much carbon dioxide; too little air, too much exhalation from lungs, 

 skin, manure, etc.; these are conditions which augment the growth 

 of disease germs and impair vitality. A cow needs hourly 3,542 

 and a horse 4,296 cubic feet of air, amounts which fill a space ten 

 feet high, ten feet wide and 35 to 43 feet long. Theoretically, perfect 

 ventilation is neither practicable nor necessary; but the conditions 

 may be better in many barns. 



Every barn is a problem unto itself, because of differences in shape, 

 in distribution of contents, in contour of land in its vicinity, in the 

 relationship of its structure to the direction of prevailing winds, as 

 well as in the number, location and character of animals, etc. How- 

 ever, some of the principles which have been worked out are sug- 

 gestive and helpful. These are: 



1. Entrance of the fresh air near the ceiling of the stable by an 

 indirect line, or by conduit into the barn near the cow's mangers. 



2. Removal of the foul air from points near floor or near ceiling, 

 either exit to be available as needed. 



3. As straight, tall and simple a stack (ventilator) as practicable; 

 as few angles as may be in side shafts; no horizontal lines what- 

 soever. In fact a good ventilating shaft should be as near an ap- 

 proximation to the form of a chimney as is practicable; should be 

 airtight, should rise high above the roof, be located as near the 

 center of the stable as may be and should have a liberal cross sec- 

 tion. It is a good notion to sheathe a metal ventilating flue with 

 wood and to use building paper on a wooden one. A chilled chim- 

 ney does not draw well; and the chilling of a barn ventilating flue 

 seriously impairs its efficacy. 



It has long been known that the fodder and the bedding, the ex- 

 terior of the cow and her milker, the utensils and the dairy, were all 

 sources of the bacterial contamination of milk. It has been taught 

 until recently, however, that the cow herself, if healthy, was not 



