July 7, 1916] 



SCIENCE 



nations), used 'by Clarke in deriving the 

 figure of the earth in 1880. 



The nature of the country traversed by 

 the are developed new ideas in recon- 

 noissance, signal building, triangulation and 

 methods of computing,. which have had an 

 important bearing on all subsequent work. 

 By means of it unity and consistency have 

 been secured in the geodetic work of the 

 Survey. It has proved a bond between the 

 many separate parts of the Survey's work. 

 These, at first, existed as a number of de- 

 tached portions, in each of which the datum 

 ■was necessarily dependent upon the astro- 

 nomic observations. The transcontinental 

 triangulations joined these detached por- 

 tions and made them into one continuous 

 system dependent upon the same geodetic 

 and astronomic data. 



From a higher scientific standpoint this 

 arc is a great contribution to geodesy in 

 giving data for the determination of the 

 earth's shape and size, but like any other 

 arc of a parallel, it must be combined with 

 an arc in the north and south direction to 

 obtain its full power in this respect. 



THE EASTERN OBLIQUE ARC 



In the Eastern Oblique arc the United 

 States has another arc of note, which covers 

 some 22°, and extends from the Bay of 

 Fundy to the Gulf of Mexico at New 

 Orleans. This was the direct result of 

 Hassler's plans, was the scene of his last 

 labors, and had for its main object the bind- 

 ing together of the detached surveys of the 

 harbors of the Atlantic Coast. 



Unlike the transcontinental arc, it has all 

 the elements necessary for the determina- 

 tion of the figure of the earth. It is the 

 first arc which made use, on a large scale, 

 of measurements oblique to the meridian. 

 One of its great effects on the geodesy of 

 the United States was that, through it, came 

 the rejection in 1880 of Bessel's spheroid of 



reference, and the adoption of the Clarke 

 spheroid of 1866 as the reference spheroid 

 to be used in this country. 



ASSISTANT CHARLES A. SCHOTT 



Many men took part in furnishing the 

 data for these two arcs, and in the resulting 

 computations, but no name stands forth so 

 prominently as that of Assistant Charles A. 

 Schott, the "Grand Old Man," who for 

 more than fifty years was identified with 

 the work of the Survey. His labors in the 

 field and office did much to bring this work 

 to a most successful finish, and it is fitting 

 that credit be given him for the two monu- 

 mental volumes of results which it was his 

 privilege to see completed before death 

 came. For this work, and for the work 

 done in many other lines of the Survey's 

 activities, I do not hesitate to mention the 

 work of Mr, Schott as one of the great con- 

 tributions made by the Coast and Geodetic 

 Survey to the geodesy of the world. 



The Survey was particularly fortunate in 

 having such a man in charge of geodetic 

 work ; one who could see the full wisdom in 

 the plans of Mr. Hassler, who consistently 

 worked for their fulfilment, and who was 

 able to have these plans transmitted to his 

 successors, Assistant John F. Hayford and 

 Assistant William Bowie. This furnished 

 a continuity of plan which probably stands 

 unrivaled in the scientific history of the 

 world, and has been one of the big factors 

 in the great success attendant upon the 

 geodetic operations of the Survey. 



RECENT TRIANGULATION 



Since the completion of the arcs men- 

 tioned, the Coast and Geodetic Survey has 

 added many more arcs to its system, until 

 the total length of the combined arcs is 

 more than 150° of a great circle of the 

 earth, or about three sevenths of the circuit 

 of the globe. Incorporated into the system 



