252 THE POPULAR SCIENCE MONTHLY. 



the "bottom of the well and in the mud there. It is especially 

 this mud that must be regarded as the native soil of the different 

 organisms which are to be referred to in the following article ; 

 and this at once forcibly calls to our attention the fact that 

 turbid well-water (that is, water which may be suspected of 

 holding mud - particles in suspension) should under no circum- 

 stances be used for drinking purposes. Water, clear and spark- 

 ling, from a mountain brook, or water drawn from a good well, 

 will, even under a microscope, present nothing that could arouse 

 the aversion of the drinker, or raise doubts as to its desirability 

 from a sanitary point of view. 



It is but of late that the attention of naturalists, and espe- 

 cially of zoologists, has been drawn to the peculiar kinds of ani- 

 mal life which exist in the depths of wells. Credit is due chiefly 

 to Prof. Franz Vejdovsky, in Prague, for calling the attention of 

 scientists to this realm of the animal world. Already many years 

 ago the searching eye of Science had penetrated to the greatest 

 depths of the oceans and inland seas ; untiring zeal had discov- 

 ered interesting phases of animal and plant life in dark caves and 

 grottoes, as well as on the snow-fields of the Alps. But the wells 

 had thus far been left unsearched, and here there still remained a 

 wide field for the explorer, for the making of interesting observa- 

 tions and discoveries. 



A peculiar circumstance led to a systematic examination of 

 wells in search for the organisms they might contain. The death- 

 rate at Prague had grown to be very high, and this created in 

 the mind of the public the idea that the condition of the water- 

 supply there was at fault. In 1879 a committee was appointed 

 which was to make a practical investigation into this matter. 

 At the request of this committee, Prof. Vejdovsky has, in a period 

 extending over two years, examined with the microscope the 

 water of more than two hundred wells of the city of Prague, in 

 order to study the noxious organisms suspected of existing therein. 



Of course, it is only possible to acquire knowledge of this kind 

 by obtaining a sufficient quantity of mud from the well which is 

 to be examined. This is done by sinking an apparatus especially 

 constructed for the purpose into the well-shaft. The scoop con- 

 sists of a stirrup made of iron, a foot and a half long and half a 

 foot broad, to which a bag of coarse canvas is attached. This 

 contrivance is fastened to a rope from twenty to thirty metres in 

 length, and, in order that it should sink deep into the mud, a 

 cannon-ball, weighing from eight to ten pounds, is fastened to it 

 at the proper place. 



According to the kind of well, the canvas bag is either dragged 

 over the bottom, so that it may gather up the mud, or the rope 

 is jerked up and down ; the water is thus stirred up and rendered 



