[429] SCIENTIFIC MANUAL. 143 



published. These records are valuable as far as they go, but 

 should, and will be made more complete. The temperature 

 of the soil at different depths should be determined simul- 

 taneously with that of the air, the direction of the wind, at 

 the time of each observation, should be recorded at each 

 station, the pressure of the air should be measured by 

 means of a standard barometer, the moisture of the 

 atmosphere should be measured by means of the hygro- 

 meter, and the amount of percolation of rain water meas- 

 ured by mean of the lysimeter. 



The ice has been broken a beginning has been made, 

 and progress both in accuracy and variety of research will 

 necessarily follow. 



These records kept for a series of years will be valuable 

 to the agriculturists of the State, and eventually lead to 

 instructive deductions. 



CHAPTER XIII. 



ENTOMOLOGY IN ITS RELATIONS TO AGRICULTURE. 



The injury to vegetation resulting from the depredations 

 of insects in the United Statas is estimated in millions of 

 dollars, and yet very few farmers are able to discriminate 

 between their friends and enemies in the insect world, for 

 we have friends as well as enemies, among these humble 

 inhabitants of our globe. 



In every department of the animal creation we find pre- 

 daceous animals which live upon their own species. Among 

 animals we have the canines and felines ; among birds, 

 eagles, hawks, etc. ; among reptiles, sharks, crocodiles, 

 etc. ; among fish, the trout and others ; among insects, 

 lady-birds, ichneumon flies, tiger-beetles, wasps, etc. 



By unceasing warfare upon their enemies among ani- 

 mals, reptiles and birds, farmers have been able to keep 



