SCIENTIFIC READINGS. 125 



310. Describe the Ignis Fatuus, or Jack-with-a- 

 lantern. 



311. What is the cause of Wind ? 



312. Is there any general regularity with regard to 

 the direction of the wind at any part of the earth ? 



313. Is there any regularity in England with regard 

 to the direction of the wind ? 



314. To what is the Ignis Fatuus attributed ? 



315. At what rate does a hurricane travel ? 



316. What is the name of that instrument by which 

 the force or velocity of the wind is estimated ? 



317- How does evaporation produce wind ? 



318. Required the name of that instrument by which 

 the quantity of desv is measured. 



319. Required the name of the instrument which 

 measures the purity of the air. 



320. What is the use of the Hygrometer ? 



321. Are whirlwinds common in temperate climates ? 



322. What is the Cyanometer? 



323. Required the quantity of water in tuns, annually 

 taken up by the process of evaporation. 



324. Required the weight of the water evaporated in 

 a summer's day from the Mediterranean. 



325. What would be the height of a cylindrical vessel 

 of 40 feet in diameter, capable of containing all the 

 water that may be evaporated from the Thames in a 

 summer's day ? 



326. How many tuns of water fall annually, on an 

 average, on a farm of 350 acres ; and what would be 

 the diameter of a globular vessel capable of containing it ? 



ELECTRICITY. 



327. To whom may the origin of Electricity be 

 traced r 



328. Why is this science termed Electricity ? 



329. What substances are Electrics, and why are they 

 so termed? 



