82 THE POPULAR SCIENCE MONTHLY. 



spring at Alvarado, furnishes a corroborating instance of how this law 

 of overflow operates. The spring was originally on the level of the 

 shore until the sand drifted by degrees and formed a ridge twenty feet 

 high, hut the water appeared at the top of the ridge. 



This law can be utilized in increasing the flow of water. As above 

 mentioned, it was found that, by inclosing an overflowing spring 

 tightly and allowing the inclosure to be terminated by a tube with an 

 opening carried to a level below the fountain, the flow was increased 

 because the channel was increased, and the resultant of the natural 

 forces with it. 



If an artificial connection be made with a stratum of water or 

 water-bed, as by a tube tightly set in the earth or a series of tubes, and 

 the suction-tube of a pump be attached thereto, we shall have the best 

 conditions for a utilization of this newly discovered force in obtaining 

 water for domestic purposes. The natural channels will thus be con- 

 tinued to the pump, and when this is operated (the air being lifted ofi^) 

 the new force acts as a handmaid in lifting the water. Many experi- 

 ments fully prove this. As the water-deposits di'awn upon are subter- 

 ranean they are ample for all practical purposes; and, if these facts had 

 been within the knowledge of Professor Buckland and the proposed 

 company to which he has given such prominence, London could have 

 been supplied with pure water without the least occasion for anxiety 

 that the manufactories on the banks of the river Coin would be robbed 

 of their portion. 



The force, then, which we have demonstrated may be thus formu- 

 lated : The resultant of the earth's centripetal and centrifugal forces 

 acts impulsively upon the subterranean water-deposits, and tends to 

 force them into and through the natural channels of the earth's crust. 



MARS AND HIS MOONS. 



By Professor JOHN LE CONTE, 



OF THE UNIVERSITY OF CALIFORNIA. 



THERE is no member of the solar system, with the exception of 

 our moon, which can be studied under such favorable circum- 

 stances as the planet Mars ; for, although Venus, when in inferior 

 conjunction, is nearer to us than Mars in opposition, yet Venus, at this 

 time, turns her darkened hemisphere toward the earth. Moreover, 

 although Mars does not appear so large an object in the telescope as 

 Jupiter, yet he is in reality seen on a much larger scale, not only on 

 account of his much greater proximity to us, but because, being like- 

 wise much nearer the sun, his surface is much more brilliantly illumi- 

 nated, so that a much higher telescopic power can be advantageously 



