March, 1938] Agricultural Research in N. H. 33 



the heating unit to be external and a circulating water-bath used, if 

 desired. 



2. A hemispherical shape for the wax container would be ideal, for 

 it would give the greatest working space for the smallest quantity of 

 wax. This means that all the wax would be at the same temperature, 

 which is practically impossible in a large cylindrical container. 



3. With the small wax container the need for a heated supply to 

 replenish that in the dipping vat is apparent. This can be done on any 

 stove, as the temperature need not be controlled so accurately as in the 

 dipping vat. 



To speed up the drying between the semi-scald and waxing it was 

 found that a ventilator fan with two-speed control filled the need well. 

 [Hatch Fund) 



Pneumatic Traction Equipment 



In addition to the routine life, mileage and cost records being kept on 

 tractor tires in use on the experimental farm a new problem arose during 

 the 1936-37 operations. A series of cuts appeared inside the right rear 

 tire of one of the tractors which it appeared were probably due to lug- 

 type chains or exceedingly hard ground. 



It was found that the inside fabric of the sidewall was broken at regu- 

 lar intervals all the way round the tire, some breaks penetrating to the 

 outside surface. The tire was sent to the factory for inspection and ad- 

 justment. After a study of the causes the following schedule of pressure 

 recommendations was made by the manufacturer : 16 to 18 pounds pres- 

 sure in the furrow drive tire seems necessary to prevent damage to the 

 fabric from overflexing or heating. This is six to eight pounds more 

 pressure than is recommended for ordinary work, but it is pointed out 

 that in plowing the tractor is operating on an angle and the furrow tire 

 is carrying enough additional weight so that with the extra pressure it 

 still keeps approximately the same deflection rate. 



In using chains or lugs it is necessary to keep sufficient pressure so 

 that there will not be excessive flexing of the tire as it rides up on the 

 lug and down on the tire. Twelve to fourteen pounds seems to be the 

 right pressure depending, of course, upon the size of the tire and the 

 weight of the tractor. 



'&* 



Animal Metabolism Studies 



The extraordinary influence of genetic adaptation and of season on 

 the basal energy requirements of the individual, has been indicated in 

 the studies in metabolism of cattle conducted by E. G. Ritzman in co- 

 operation with the Carnegie Institution of Washington. 



Measurements of the heat production of a Hereford cow given a 

 fattening ration were compared with that of a Holstein cow fed for the 

 production of about 25 pounds of milk. They indicate that the basal 

 metabolism of the laetating cow was about 25 per cent, greater per unit 

 of weight than that of the beef cow. 



The practical inference is that the inherited traits play a far greater 

 role in the use to which the animal body directs its food energy than 

 does the character of the food. 



