3 6z 



THE POPULAR SCIENCE MONTHLY. 



CORRESPONDENCE. 



THE WATER-HAMMER. 



To the Editor of the Popular Science Monthly. 



SIR : The following phenomenon can, 

 perhaps, be explained by yourself or 

 one of your readers : I have a water-ham- 

 mer, made of a straight tube of glass, about 

 eighteen inches long and three-quarters of 

 an inch in diameter. At the top of the 

 tube there are two bulbs, the upper one 

 about half the size of the lower, with only 

 a narrow passage of about a sixteenth of an 

 inch in width to connect the lower bulb 

 with the tube, and the upper bulb with the 

 lower. About one-third of the tube con- 

 tains water. When the tube is inverted, 

 and the water allowed to fill both bulbs, it 

 will not, upon the tube being reversed, run 

 out, but will remain in the bulbs for an in- 

 definite time, until shaken or otherwise 

 disturbed. This may be owing to adhesion 

 simply, or, possibly, to capillary attraction, 

 but it is not to this fact chiefly that I wish 

 to call your attention. The water being in 

 the bulbs, and the tube held with 

 the bulbs upward, if a smart blow 

 with the palm of the had be ap- 

 plied at the bottom of the tube, 

 there arises, under certain con- 

 ditions which I have been unable 

 to determine, a ringing noise re- 

 sembling sometimes the singing 

 of a bird, sometimes the noise 

 produced by a thin iron instru- 

 ment a fork, for instance when 

 knocked rapidly against an empty 

 tumbler. During this time, no 

 water escapes from the bulbs, but 

 the water at the mouth of the 

 lower bulb is violently agitated, 

 as if small particles of air were 

 quickly ascending to the height 

 of a quarter of an inch in the bulb. 

 Not a drop of water is displaced, 

 the water remaining at the bottom 

 of the tube not being perceptibly 

 increased while vhe noise contin- 

 ues. It lasts sometimes from five to ten 

 minutes, and it seems as though, under fa- 



vorable conditions, it might continue in- 

 definitely. Very frequently, however, the 

 experiment does not succeed, though ap- 

 parently all the conditions are exactly the 

 same. Here, therefore, are two questions : 



1. Wliat is the reason why the water, 

 when caused to enter the bulbs, does not 

 flow out of them when the position of the 

 tube is reversed, but remains stationary as 

 if there was no such thing as gravity, and, 

 in this case, a vacuum besides ? 



2. What is the reason of the singing 

 noise above described ? G. M. 



New Yobk, March 23, 1S76. 



To the Editor of the Popular Science Monthly. 



Will you allow me to state the precise 

 ground of objection to your criticism of my 

 book, " The Sexes throughout Nature ? " 

 " What she proposes to do," you affirm, "is 

 nothing less than to reduce the whole organic 

 world, with all its vital and physical char- 

 acters, into exact and demonstrable quanti- 

 tative expression." 



I only insist that, until science can offer 

 us exact quantitative proof that the total 

 of male characters is in excess of the total 

 of female characters, no scientist should as- 

 sume to determine, on scientific authority, 

 that woman is inferior to man. I make no 

 attempt to place my hypothesis, that, in 

 each species of being, the sexes are true equiv- 

 alents, on a " demonstrable quantitative " 

 basis. 



Though presented in the form of equa- 

 tions, and defended in a series of carefully- 

 argued propositions, the theory waits to be 

 tested experimentally and quantitatively. 

 It assumes to be nothing but a provisional 

 hypothesis, destined to be either confirmed 

 or rejected, as it is found to agree or not to 

 agree with the decisive facts of Nature. I 

 merely offer various evidence in defense of 

 the assumption that, physical powers com- 

 pared with physical, and psychical powers 

 with psychical, the female is everywhere 

 the equal of the male of its own species. 



