JsNE 16, 1922] 



SCIENCE 



645 



the field it would pass from one to another of 

 those remaining on the outside of the nest and 

 offer the new nectar which was eagerly ac- 

 cepted. From five to a dozen individuals 

 would thus be fed before passing inside the 

 nest where it was lost to sight. 



This and other species of Nectarina are dis- 

 cussed at length by R. du Buysson in Annates 

 de la soeiete entomologique de France, Vol. 74 

 pp. 537-566. 



Frank C. Pellett 



Hamilton, III. 



SCIENTIFIC BOOKS 



Geodetic Operations in the United States, Jan- 

 uary 1, 1912, to December 31, 1921. By 

 William Bowie. Pp. 26, illustrated. 

 (Washington, Government Printing Office, 

 1922, 20 cents). 



This is a report which was presented in Rome 

 in May, 1922, at the meeting of the section of 

 Geodesy of the International Geodetic and 

 Geophysical Union. It is reviewed from the 

 point of view of a scientist. Othei'wise the 

 reviewer might call attention more directly to 

 certain points in the report which are of inter- 

 est to any one who would like to see all of the 

 United States mapped well and soon. 



The perusal of this publication, showing the 

 contributions to geodesy by the Coast and 

 Geodetic Survey in the past ten years, arouses 

 admiration for the rapid progress which has 

 lieen made in spite of the delays and disturb- 

 ances due to war. The rate of accumulation of 

 new observations for use in geodesy has been 

 greater in the United States in this decade than 

 in anj' previous decade. Along Avith this 

 progress in observing there have also been 

 notable improvements in instruments and 

 methods. 



One hundred and twenty-four determinations 

 of the intensity of gravity, corrected for topog- 

 raphy and isostatic compensation, were avail- 

 able in the United States before 1912. In the 

 past ten years 162 such determinations have 

 been added, making the total now available 286. 

 This is a very substantial addition to the data 

 of geodesy. 



There are two lines of attack on the problem 

 of determining the figure and size of the earth 



and on all associated matters such as isostasy. 

 These two lines together are substantially the 

 whole of geodesy. The primary data for one 

 line of attack are observed values of the inten- 

 sity of gravity as given by pendulum observa- 

 tions. The primary data for the other line of 

 attack are observations of the relative direc- 

 tions of gravity at various places as given by 

 astronomic determinations of the latitude, 

 longitude and azimuth of points connected with 

 continuous triangulation. The preceding para- 

 graph shows that the available data for the 

 first mentioned line of attack has been more 

 than doubled in the United States in the past 

 ten years. The paragraphs which follow give 

 some of the points from the report which show 

 that the strength available for the second line 

 of attack mentioned has also been greatly 

 increased on this continent in the past decade. 



During 1912-1921 102 determinations of 

 astronomic azimuth scattered widely over the 

 United States have been made. The total num- 

 ber of such azimuth determinations before 1912 

 was 285. Similarly in this decade more than 

 one fourth has been added to the number of 

 determinations of astronomic longitude in the 

 United States and 124 determinations of astro- 

 nomic latitude have been made. To the net- 

 work of primary triangulation in the United 

 States which existed before 1912 there has been 

 added in the last decade arcs of an aggregate 

 length of 4,659 miles, or more than 66 degrees 

 of a great circle on the earth's surface. Clarke's 

 classical computation of the figure of the earth 

 in 1880 depended on arcs measured by various 

 nations of an aggregate length of only 89 de- 

 grees. In connection with the new triangula- 

 tion of the past decade 20 new base lines have 

 been measured with probable errors of one part 

 in a million as a rule. 



The aceui-acy with which the figure and size 

 of the earth may be derived from a given con- 

 tinuous network of triangulation and the con- 

 nected astronomic determinations increases 

 very rapidly as the extreme dimensions of the 

 network are increased. Within the decade 

 under consideration, by cooperation on the part 

 of Canada and Mexico, the continuous trian- 

 gulation has been extended from the United 

 States far into each of these countries and the 

 computations are made on one standard datum. 



