210 EXPERIMENT STATION. [Jan. 



may be of assistance in case of donbt, and that they may in time 

 become fully reliable. However, there is so much at stake when 

 a bog promises a good crop that it will probably be best for the 

 growers to provide themselves with the necessary instruments 

 and learn to make their own forecasts, because there is such a 

 variety of conditions in different parts of the Cape. 



The season's records seem to show that the early evening dew 

 point, which has been shown to be of no value as an indicator of 

 the minimum night temperature in som« parts of the country, 

 can be relied upon to a considerable extent in forecasting such 

 temperatures on the Cape. The records further seem to show 

 that the best indications that a frost may be expected on any 

 night during the usual period of frost danger are the fol- 

 lowing : — 



1. Low dew point (50° F. or below at substation shelter). 



2. High (above 30) and rising barometer. 



3. An all day's wind from a northerly, northeasterly or north- 

 westerly direction, dying out in the early evening. 



4. A clear sky. 



5. A low maximum day temperature. 



6. A low and falling early evening temperature. 



The readings of the maximum and minimum thermometers 

 and the amount of precipitation were telegraphed to the office of 

 the United States Weather Bureau at Boston every morning 

 after April 25 during the sj)ring and fall periods of frost 

 danger. 



2. Feost Peotection. 



Because of the failure of a circulating pump, it was impossi- 

 ble to carry out tests with the Skinner system, as had been 

 planned, during the spring frost period. Certain apparent 

 disadvantages connected with the use of this system for frost 

 protection have been discovered. In the first place, the p-ump 

 and engine required for supplying water under the necessary 

 pressure for a system covering several acres are more expensive 

 than at first supposed. The Skinner Irrigation Company states 

 that it is necessary to sprinkle most crops with water every two 

 minutes during a frosty night in order to afford sufficient pro- 

 tection. It seems possible, however, that the injury caused 

 by frost may be prevented by sprinkling the frosted plants 



