334 



SCIENCE. 



[Vol. V., No. 116. 



in the service, made a determined effort to 

 defeat it, which was only so far successful as 

 to defeat it in the senate once of the three 

 times it was there considered after leaving the 

 house of representatives, where it was passed 

 by a small majority. By some it is believed 

 that the whole proceeding originated in repub- 

 lican party warfare against the ' mugwumps ' 

 and free-traders at Yale college. This much 

 is certain, that the ordinary friendliness which 

 might exist between the college and the state 

 was lacking in the case of many members of 

 the general assembly. The governor, who 

 was known to be personally strongly in favor 

 of the observatory service, found himself in a 

 delicate position, and doubtless, in the absence 

 of any thing unconstitutional in the repeal, 

 took the only course open to him which would 

 be open to no misconstruction. 



We copy this with heart}^ emphasis and ap- 

 proval, for it points out precisely the difficulty 

 under which our scholars labor. But while 

 in Great Britain, and in continental Europe 

 generally, the surveys from which good school- 

 maps might be constructed are already well 

 advanced or completed, in our country they 

 are either neglected or only just begun ; and it 

 is even still almost always a difficult matter to 

 persuade state legislators, from whom appro- 

 priations flow, that good maps are needed. It 

 is no exaggeration to say that the educational 

 value of such maps as are now in preparation 

 in New Jersej^ and Massachusetts is alone 

 more than their cost to the state ; and we shall 

 watch for the better teaching in the common 

 schools, that must follow their completion, 

 with as much interest as for the inception of 

 similar work in other states. 



Professor James Geikie of Edinburgh con- 

 tributes a very valuable article on the physical 

 features of Scotland to a recent number of the 

 new Scottish geographical magazine. It is 

 illustrated by a beautiful little orographical 

 map of Scotland bj^ J. Bartholemew, in which 

 the plrysical relief is finely brought out. Com- 

 menting on this, and on the excellent maps 

 of the Ordnance surve} T on which it is based, 

 Professor Geikie concludes with the following 

 paragraph : — 



" With such admirable cartographical work before 

 them, how long will intelligent teachers continue 

 to tolerate those antiquated monstrosities which so 

 often do duty as wall-maps in their schoolrooms ? 

 Surely more advantage ought to be taken of the 

 progress made within the last thirty or forty years in 

 our knowledge of the physical features of our coun- 

 try. It is time that the youth in all our schools 

 should be able to gather from their maps an accurate 

 notion of the country in which they live; that they 

 should see the form of its surface depicted with an 

 approach to truth, and learn something more than 

 that so many principal rivers flow in so many differ- 

 ent directions. With a well-drawn and faithful oro- 

 graphical map before him, the schoolboy would not 

 only have his labors lightened, but geography would 

 become one of the most interesting of studies. He 

 would see in his map a recognizable picture of a 

 country, and not, as at present is too often the case, 

 a kind of mysterious hieroglyphic designed by the 

 enemy for his confusion." 



LETTERS TO THE EDITOR. 



Centrifugal force and the supposed polar 

 ice-cap. 



In your issue of March 27, you publish an article 

 by Dr. Franz Boas, upon ' Mr. Melville's plan for 

 reaching the north pole,' in which there are some 

 statements that should not pass unchallenged. They 

 occur in the discussion of the effect, upon the sup- 

 posed ' ice-cap,' of centrifugal force due to the earth's 

 rotation. 



The formula for calculating the effect of centrifu- 

 ge 2 

 gal force is a well-known and simple one, C - 02 r% > 



in which v = velocity in feet per second, r = radius 

 in feet, w = weight of the mass acted on, and C is 

 the centrifugal force in pounds. Apply this to lati- 

 tude 85°, r = 345 miles, or 1,821,600 feet, and v = 132| 

 feet per second. 



Then, if we take a cubic foot of ice, C = ■£§ of a 

 pound, or about one hundred grains of pull, away 

 from the pole, southward, upon each cubic foot of 

 ice, — a force which is approximately one four- thou- 

 sandth of the weight of the body acted upon, instead 

 of being thirty thousand times that weight. 



Whether the ice is one foot thick, or one hundred 

 feet in a single block or in a broad or heaped mass, 

 makes no difference in the result; for each unit of 

 mass acts independently of each other unit. So far 

 as centrifugal force goes, it could neither make nor 

 mar the hypothetical ' ice-cap.' 



E. W. Wetmore. 



Essex, Conn., April 11. 



In the controversy between Mr. Melville and Dr. 

 Boas respecting the supposed polar ice-cap, both par- 

 ties appear to take an erroneous view of the action 

 of ' centrifugal force.' 



