DAIRY CATTLE AND THE DAIRY FARM 129 



ventilation of farm buildings. Their researches include experiments 

 with the King system, The Rutherford system, with ventilation through 

 pierced walls, and with ventilation through muslin curtains. 



These authors state that they find the King system unsatisfactory 

 in the climate of Ottawa and suggest that it is better suited for warmer 

 countries. 



Rutherford System. They find that in Canada the Rutherford 

 system gives the best results. It is built on the theory that the venti- 

 lated warm air will rise in spite of the high specific gravity consequent 

 on its high content of carbon dioxide gas and water. They believe 

 that with the Rutherford system there is less tendency for moisture to 

 precipitate from the admixture of cold air with moist warm air than 

 with the King system. The fresh outside air enters the stable at or near 

 floor level through inlets that pass under or pass through the barn walls 

 while the foul air is carried off through one or more outlet ducts built 

 of boards running vertically, two-ply, with an inch air space and two 

 papers between them. The air space provides insulation against cold 

 and so prevents condensation of moisture in the duct. These ducts 

 are carried to the ridge of the roof and are hooded, having 15 in. of air 

 space between the mouth of the duct and the wood. In stables where 

 600 to 800 cu. ft. of air space is provided for each cow 2 years old and over, 

 there should be 15 sq. in. or somewhat more of controlled outlet area 

 and 8 sq. in. or slightly more of controlled inlet area per cow. Controls 

 or dampers are needed because cold air, being much heavier than warm, 

 causes more rapid inflow and outflow of air in very cold weather, than 

 in warm, making it necessary to control the circulation to prevent barns 

 becoming too chilly in cold weather and too warm in hot. 



The advantages claimed for the Rutherford system are : 



1. Ease of installation in both old and new buildings. 



2. Adaptability to all classes of stables. 



3. Suitability to variety of weather and climate. 



4. Facility of operating and controls. 



5. Effectiveness of control of all the stable. 



Ventilation by Pierced Walls. Ventilation by pierced walls was found 

 to be simple and cheap ; round or square holes are pierced in all the sides 

 of the stable exposed to outside air. In a stable 30 by 36 ft. these holes 

 should be 4 in. in diameter and spaced 3 ft. apart, or they should be 6 in. 

 in diameter and be placed 6 ft. apart. The holes may pass straight through 

 the walls thus giving a direct current, or in walls built with an air space 

 a hole may be placed on the outside between the studs near the ground 

 and one on the inside a little above the catties' backs, thus giving a de- 

 flected current in the space between the walls. The air enters the barn 

 through the holes on the side exposed to the wind and the stable air es- 

 capes through the other holes, consequently holes that on one day serve 



