F. GEOGKAPHY. 259 



feature of the state lie in directions which are diagonals be- 

 tween the cardinal points of the compass, showing, as Win- 

 chell thinks, that these axes are the resultant of two forces: 

 a glacial force acting from the northeast, and a stratigraph- 

 ical acting along the lines of strike of the rocky formations. 

 The effect of the lake's temperature has received very full 

 attention at the hands of Professor Winchell, who seems to 

 have been the first to give us an exact idea of the great ex- 

 tent of that influence. Fifty-five meteorological stations in 

 Michigan, and an almost equal number of stations in the 

 neighboring states, have been employed by him in tracing 

 out and marking the tortuosities of the isothermals of the 

 lower peninsula of Michigan. The important facts disclosed 

 by his researches in this respect have already been published 

 widely in many journals, both in this country and in Europe ; 

 and these disclosures are destined to take their place among 

 the most interesting phenomena of climatological -science. In 

 reference to the rainfall, he infers from the data at hand that 

 the year 1871 was a year of remarkable dryness throughout 

 the state. 



THE TRIGONOMETRICAL SURVEY OF INDIA. 



From the general report of the operations of the great 

 trigonometrical survey of India during 1873 and 1874, we 

 gather, that of the principal triangulation, seventy triangles, 

 covering 7200 square miles, have been measured. The sec- 

 ondary triangulation extends over an area of 20,000 square 

 miles, of which 5200 have been closely covered with points 

 for use in plane table surveying. Of this latter an area of 

 500 square miles has been completed on a scale of one inch 

 to the mile, and an area of 2400 square miles on a scale of 

 two inches to the mile. The revision of the older portions 

 of the triangulations has now been completed, and the whole 

 of the work corresponds to the demands of modern science. 

 Certain of the stations on the sand-hills formerly occupied 

 by the observers having disappeared, it has been ascertained 

 that these hills travel progressively in the same direction, 

 W.N.W. to S.S.E., which is that of the prevailing winds in 

 this locality. The rate of progression appears to be about 

 fifty feet per annum ; and this remarkable sand-wave, which 

 has never yet been effectually resisted, notwithstanding nu- 



