The only difficulty was the same as with all surface heat- 

 ers that when not perfectly level the milk would run on one 

 side only. 



Mr. A H. Barber, of Chicago, who made this cooler, 

 improved on this by making it as illustrated in Fig. 69, giving 

 a view from above with part exposed 

 and a cross section X M, which shows the 

 corrugation which compels the milk to run 

 in the little gutters and increases the cool- 

 ing surface. Also in P the partitions 

 which turn the current of the water which 

 flows as the arrows show on the exposed 

 part of the sketch. The milk flows, of 

 course, in the opposite direction and on a 

 length of 8 feet, 2 inches drop is fully 

 enough; indeed, they may be placed nearly 

 level. 



Where they are not desired to be used as 

 conductors as well as coolers they may be 

 arranged zig zag, as shown in Fig. 24. 



In a trial I made, 22 feet of this cooler 

 reduced 900 fibs, per hour from 156 to 102 

 with the cooling water 74, and the next 

 20 feet reduced it to 55 with water circu- 

 lating over an ammonia coil (about 90 feet, 

 1 inch) which kept the water at 50. 



Mr. Barber makes these double width to 

 order for pasteurizing purposes, and, if de- 

 sired for brine circulation they are made of 

 Fig. 69. tinned copper. 



Numerous other surface coolers for running water have 

 been devised, but these are the principal ones. 



We now come to the coolers with protected surface. 

 W T hile I feel inclined from a practical standpoint to over- 

 look the demand of bacteriologists for a heater with covered 

 surface, I am more inclined to acknowledge the value of 

 protection against the air during cooling, especially the last 

 cooling. 



Prof. Russell suggests the one shown in Fig. 70. It con- 

 sists of two tin cylinders with only J-inch space between each 

 other, and here the milk flows through (MC). The cylinders 

 can be taken apart at one end and inlet and outlet pipes can 



