57° 



POPULAR SCIENCE MONTHLY 



its use is attended with no harmful results 

 to the patient. The complete address, with 

 some interesting illustrations, appeared iu 

 the American Journal of the Medical Sciences 

 for December, 1897. 



Artesian Wells in Iowa. — The artesian 

 field of Iowa is described by Mr. W. H. Nor- 

 ton as being only a part of an extensive ba- 

 sin which may be termed the artesian area 

 of the upper Mississippi Valley. It includes 

 a part of Missouri, a large part of Illinois, 

 southern Wisconsin, and southern Minnesota. 

 The intake of the whole field lies in the two 

 States last mentioned. The size of the in- 

 take area is roughly estimated at about four- 

 teen thousand five hundred square miles. 

 With the whole Iowa field, it lies withiu a 

 region of abundant rains, enjoying a mean 

 annual rainfall of not less than thirty-two or 

 thirty-three inches. On the basis of De 

 Ranee's estimate that one inch of rainfall 

 per year is equivalent to 14,555,280 imperial 

 gallons to the square mile, or a daily average 

 of 40,000 gallons to the mile, the total an- 

 nual rainfall of the collecting area of the 

 Iowa artesian field may be estimated at 

 about 475,000,000 gallons to the square 

 mile, a daily average of 1,280,000 gallons or 

 a total annual precipitation for the entire 

 collecting area of 6,887,500,000,000 gallons. 

 Only what of this water does not go into the 

 streams and escape by evaporation is avail- 

 able for the artesian reservoir, but there is 

 every reason for believing that that which 

 falls over the collecting area is more than 

 sufficient to meet all the demands made upon 

 it by the Iowa wells. 



Submarine Land Slides and Telegraphic 



fables. — While the general result of denuda- 

 tion on the land is to bring material to a 

 lower level, and, by gradually wearing away 

 excrescences like mountain heights, to render 

 such forms more stable, beneath the sea, as 

 Prof. John Milne pointed out at the British 

 Association, such materials are accumulated 

 in slopes, which become unstable as the de- 

 posits grow, and facial slidings take place 

 from time to time. The movements are 

 caused by gravity, by subterranean springs, 

 and by submarine earthquakes, the effects of 

 which are at least equal to those we see pro- 

 duced on land, and probably greater. These 



slidings, occurring along the edges of subma- 

 rine banks and of the submerged continental 

 frontier, are very damaging to telegraphic 

 cables, which are apparently buried under 

 large bodies of material. Sometimes two 

 or three cables, ten or fifteen miles apart, 

 have been destroyed by such slides. Earth- 

 quakes have been felt on land at the same 

 moment that a cable has been broken, and 

 the ocean has been thrown into a state of 

 agitation for one or two days. Under very 

 great disturbances of this kind the resultant 

 earth movement might be recorded, with 

 suitable instruments, at any point on the 

 surface of the globe. In the most remark- 

 able disturbances recorded, changes of depth 

 up to two hundred fathoms have taken place 

 over considerable areas. The study of these 

 dislocations should be established on all the 

 continents and oceanic islands. 



School Sessions and Health. — In order to 

 obtain a consensus of opinion on the subject, 

 eight questions bearing upon the influence of 

 our school system on the health and develop- 

 ment of the child were addressed by Dr. E. 

 Stuver, of Rawlins, Wyoming, to about one 

 hundred and fifty educators and physicians 

 of the country. Twenty-nine out of sixty- 

 three educators and thirty out of thirty-five 

 physicians did not think our present compre- 

 hensive course of study best calculated to de- 

 velop the highest physical and intellectual 

 powers of the child, and some of the re- 

 spondents condemned these courses severely. 

 Eighteen educators and one physician were 

 doubtful. Respecting the proper length of 

 continuous school sessions, the average of 

 one hundred opinions were in favor of not 

 longer than one hour or an hour and a half. 

 While considerable divergence appeared con- 

 cerning the limit of length of a single recita- 

 tion, the majority of respondents advocated 

 from ten to tw T enty minutes in the primary 

 and from twenty to thirty minutes in the 

 grammar grades ; but much was thought to 

 depend upon the nature of the subject of the 

 lesson, the method of instruction, and the 

 kind of teacher. Frequent recesses met 

 much favor, and many respondents advised 

 one every hour. Of one hundred and five 

 opinions expressed as to the relative merits 

 of open-air recesses with spontaneous play 

 and of formal indoor exercises, all except 



