PERIOD OF LACTATION 323 



draws the air from the pipes and actuates the pulsators. 1 

 The pulsator in turn operates the teat-caps, which consist 

 of white metal tubes large enough to admit a cow's teats of 

 any size, lined with thin flexible indiarubber tubing, which by 

 a series of contractions and expansions manipulate the cow's 

 teats in imitation of the action of a calf, thereby extracting 

 from the udder, in from six to ten minutes, the milk which runs 

 into the milk-pail. The upper end of each flexible rubber 

 tube is folded back over the open end of its metal cap, which 

 it clasps, to make a close joint to permit of the contraction 

 and expansion of the rubber by means of air forced by the 

 action of the pulsator between it and the metal casing which 

 it lines. Experience has shown that a man or a dairymaid 

 with an assistant to carry away the milk, can with one 

 pulsator easily milk per hour 15 to 20 cows ; and an intelli- 

 gent operator can attend to four pulsators at the same time, 

 consequently the labour of attending four pulsators is little 

 more than that required for one. The apparatus suitable for 

 dairies of 20 to 100 cows ranges in cost from 50 to ;ioo, 

 and the advantages are much greater on a large than on a 

 small scale. In the latter case it is more a matter of con- 

 venience when labour is not to be had than one of saving 

 outlays ; and it is not likely to rapidly replace the hinds' 

 wives on a mixed arable and dairy farm, who are able and 

 willing to milk for the sum of 33. 6d. per week. Any of 

 the common sources of power on the farm are suitable to 

 produce the vacuum for working through the medium of an 

 air-pump, which is pronounced more reliable than a steam 

 ejector. The oil-engine has so far proved the most con- 

 venient form of power in this country. The apparatus is 

 easily cleaned, and if this be done with reasonable care the 

 milk keeps sweet longer than when drawn by hand, as 

 contact with injurious germs is avoided. 



The usual period of lactation is between nine and ten 

 months, giving the cow a rest of two or three months to 

 prepare for the next milking period. Cows naturally take 

 this time, more or less ; but they are to a considerable extent 

 affected by the kinds and quantities of food given, and by the 

 general treatment. Some continue to yield milk till the 



Another successful machine, made by Wallace, Castle Douglas, N.B., 

 has four pulsators, one for each teat, in place of one. 



