EXPERIMENT STATION. 



29 



sound, as against more than fifty per cent in case of those still 

 at Boston. 



The following table shows the percentages of sound apples 

 in wrapped and unwrapped lots, with difference. 



These figures, except in 4 and 8, are in favor of the wrapped 

 ones. Later examinations of the first five boxes which were 

 kept in the station cold storage after their return showed the 

 same result. 



April 20, a comparison of the first four boxes with the check 

 indicated that they had not kept as well since their return as 

 those stored at home; but May 29, a larger percentage of those 

 that had been in the Boston storage were sound than in case 

 of the' check. 



Silo Tempekatures Taken by Electricity. 



In the study of the biology of ensilage it is important to 

 know the temperatures to which it is subjected. Only a small 

 portion of the contents of a silo is accessible to the ordinary- 

 thermometer, — that portion near the surface. The following 

 is an account of an experiment in taking the temperatures in 

 the depth of the silo by electrical apparatus. The principle 

 on which it is based is the fact, well known in physics, that 

 changes in temperature cause changes in the resistance which 

 different materials offer to the passage of an electric current. 

 The resistance is readily measured with appropriate apparatus, 

 and from it can be calculated the temperature. The part of 

 the apparatus which is directly subjected to the changes in 

 temperature, called an electrode, may consist of wire or other 

 metallic body through which an electric current can be passed. 

 When a metallic electrode is used the higher the temperature 

 the gi'eater the resistance offered and vice versa. 



