538 



SCIENCE 



[N. S. Vol. XXXIII. No. 849 



Results similar to those recorded in the 

 table here given have been obtained in a much 

 more extensive study of heredity in feeble- 

 mindedness which was recently reported by 

 Goddard.^ A. J. Eosanoff 



State Hospital, 

 Kings Park, N. Y. 



TSE TEXAS-CALIFOENIA AEG OF PEIMAEY 

 TEIANGULATION 

 A GREAT arc of primary triangulation more 

 than 1,200 miles in length, extending from 

 central Texas to the Pacific coast, has just 

 been completed by the Coast and Geodetic 

 Survey. It connects the 98th meridian pri- 

 mary triangulation in the vicinity of Weather- 

 ford, Texas, with the Pacific coast primary 

 triangulation in the vicinity of San Diego, 

 California. 



It is connected with the United States and 

 Mexican Boundary at a number of places and 

 is joined to and correlates a number of de- 

 tached government surveys. It furnishes the 

 geographic positions on the U. S. Standard 

 Datum, of more than two hundred points 

 which can be used to control all future public 

 surveys within the region traversed. 



There are 92 primary stations in the main 

 scheme of this triangulation and, in addition, 

 38 stations in secondary schemes which pro- 

 vide for the connections with United States- 

 Mexican boundary monuments and existing 

 triangulation. The total area covered by the 

 triangulation is 48,400 square miles, the average 

 length of line east of El Paso is 17 miles, and 

 from that place to the Pacific coast it is 62 

 miles. The maximum length of line is about 

 120 miles. The observations were made with a 

 12-inch theodolite, the pointings being made 

 on heliotropes and acetylene lamps mounted at 

 the stations observed upon. During the prog- 

 ress of the triangulation two primary bases 

 were measured and 24 primary azimuths were 

 observed. 



The reconnaissance for this work was made 

 between September, 1907, and February, 1908, 

 and the observing was done in three seasons 



- Amer. Breeders Magasine, Vol. I., No. 3. 



between November, 1908, and February, 1911. 

 The total work was done in less than three 

 years and six months, and the observations in 

 less than two years and four months. 



While the Coast and Geodetic Survey has, 

 in the past, made more rapid progress on 

 primary triangulation in the United States 

 than that made in any other country, yet the 

 rate of progress on the Texas-California arc 

 exceeds that on any other are in this country 

 and the unit costs per square mile of area cov- 

 ered by the main scheme and per mile of prog- 

 ress are only about one half those of the tri- 

 angulation between Marysville, Cal., and 

 Tacoma, Wash., the arc for which, previously, 

 these unit costs were the lowest. The accu- 

 racy, as measured by the closing errors of 

 triangles of the Texas-California arc, is 

 greater than that specified in the requirements 

 for such work. 



The remarkable rapidity of progress and 

 the low cost of the work were largely due to 

 the small amount of . camp equipage used by 

 each unit of the party; to the fact that only 

 two ofiicers had charge of field work, the 

 writer on reconnaissance and a portion of the 

 first season's observing, and Mr. J. S. Hill on 

 the remainder of that season's work and that 

 of the succeeding two seasons; and to the 

 services of a most efficient signalman, Mr. J. 

 S. Bilby, who was attached to each party 

 from the beginning of the reconnaissance to 

 the end of the observing. The parties were 

 organized and managed, in the main, in a 

 manner similar to that of the parties engaged 

 on other pieces of primary triangulation done 

 by this survey in recent years, only such 

 changes being made as were necessary to meet 

 new conditions which were encountered in 

 semi-arid and arid sections, much of which 

 was also mountainous. 



This arc of primary triangulation will not 

 necessarily be discussed separately by this sur- 

 vey in investigations of the figure of the earth, 

 as were the two great arcs, one extending 

 across the continent along the 39th parallel of 

 latitude and the other paralleling the Atlantic 

 coast from Maine to the Gulf, and known, re- 

 spectively, as the " transcontinental arc " and 



