37 6 THE POPULAR SCIENCE MONTHLY. 



between the water-columns R and Z. The water in R becomes heated 

 by contact with the imprisoned steam, and will obviously attain a 

 higher temperature in the lower than in the upper part of the geyser- 

 tube R. Superheated water is produced in R as well as in Z, because 

 the weight of the water in R and the upward pressure of the water, 

 and the confined steam in Z, produce pressure and counter-pressure. 

 As steam and water continue to rise from the channels V, the level of 

 the water in x y is depressed, for the steam can exercise its force only 

 in the direction of R. As the expansive force of the steam increases, 

 a greater quantity of water is driven over the rim of the basin till the 

 force of the steam becomes so great as to exceed the weight of the 

 column of water in R. Single puffs of steam escape, the elastic force 

 of the vapor is slightly diminished, and a sudden development of steam 

 is produced from the superheated water in Z, causing the whole col- 

 umn of water in R to be thrown forcibly into the air. The super- 

 heated water which has got into R during this movement is likewise 

 converted into steam, increasing the effect. The conditions required 

 by the last theory for the origin of an intermittent spring exist in nat- 

 ure. Volcanic forces produce suitable crevices, and the water, leaving 

 siliceous deposits upon the walls, makes these clefts steam-tight. 



The time which elapses between two successive eruptions varies in 

 different intermittent springs. It depends upon the length and breadth 

 of the whole geyser-shaft, and the distance to which it penetrates to- 

 ward the interior of the earth. The temperature of the superheated 

 water and the amount of steam that is formed from it are also largely 

 dependent on the size of the spring. Thus, Strokr and the Little Gey- 

 ser, intermittent springs in Iceland, also lying at the foot of Bjarna- 

 f ell, have much stronger eruptions than the Great Geyser. The inter- 

 mittent springs of the North Island of New Zealand are distinguished 

 by their beautiful snow-white deposits of siliceous sinter, within which 

 the water of the basin appears blue. The most imposing of known 

 geysers are those of North America, of which the Giant shoots its jet 

 to the height of two hundred and fifty feet. 



-- 



A PREMATURE DISCUSSION. 



By Mrs. Z. D. UNDEEHILL. 



IN her clever article upon " Science and the Woman Question," in 

 "The Popular Science Monthly" of March, 1882, Miss Hardaker 

 arrives at the definite conclusion that woman is and must necessarily 

 for ever remain the intellectual inferior of man. In view of the im- 

 portance of this conclusion, it will perhaps be worth while for a critic 

 committed to neither side of the question to point out several flaws in 



