558 



SCIENCE 



[N. S. Vol. XXXI. No. 797 



Dr. W. J. Humplireys, of the U. S. Weather 

 Bureau, then spoke informally on " Solar Dis- 

 turbances and Terrestrial Temperatures." 



The speaker's purpose in this paper was to 

 bring harmoniously together, as cause and effect, 

 some solar and terrestrial phenomena. 



The sun being the source of practically all of 

 the radiant energy we receive, any change in its 

 surface that affects its radiation must, through 

 the resulting modification of the energy received, 

 also affect certain terrestrial phenomena, some of 

 which are of vital importance. 



The speaker briefly discussed the relation of the 

 changes in the number and extent of sun-spots, 

 flocculi and coronal streamers to such terrestrial 

 phenomena as auroral displays, magnetic storms, 

 temperature changes and plant growth, and 

 pointed out how some of these relations may be 

 explained. 



The following conclusions were reached in refer- 

 ence to the relation of changes in sun-spots and 

 auroral discharges to terrestrial temperatures: 



1. An increase in sun-spots appears certainly to 

 be accompanied by a decrease in terrestrial tem- 

 peratures fully twenty fold that which can be 

 accounted for by the decrease in radiation from 

 the spot areas alone. 



2. It seems nearly certain that sim-spot maxima, 

 whatever the value at such times of the solar con- 

 stant, must lead to a decrease in the ultra-violet 

 radiation that reaches the earth, and a correspond- 

 ing decrease in the production, by this method, of 

 ozone in the upper atmosphere. 



3. The increase in the auroral discharges that 

 accompany spot maxima tend to increase the 

 amount of ozone. 



4. The change in temperature of the earth, and 

 all its train of consequences, from spot maximum 

 to spot minimum, is not necessarily dependent 

 upon a change in the solar constant. It may 

 depend largely, if not wholly, upon a change in 

 the absorptive property of the atmosphere, caused, 

 we believe, by a variation in the amount of ozone 

 produced by ultra-violet radiation and by auroral 

 discharges. 



The 678th meeting was held March 12, 1910, 

 President Woodward presiding. Two papers were 

 read: 

 Recent Work on Primary Triangwlation in the 



Southwest: Mr. Wm. Bowie, of the Coast and 



Geodetic Survey. 



After having completed the primary triangula- 

 tion along the 98th meridian, in 1907, it was 



decided to extend the scheme from the 98th 

 meridian, in central Texas, westward to the 

 Pacific coast. This area in the southwest section 

 of the country was badly in need of a control 

 upon which to base surveys and engineering work. 



It was originally intended that the portion of 

 this scheme in the state of Texas should run along 

 the Eio Grande River, from Brownsville to El 

 Paso. This plan was abandoned owing to many 

 difficulties which would have been encountered. 

 The route used starts from the 98th meridian in 

 the vicinity of Weatherford, and follows the 

 Texas and Pacific Railroad across the state of 

 Texas to El Paso, thence across the southern por- 

 tion of New Mexico, Arizona and California to the 

 Pacific coast triangulation in the vicinity of San 

 Diego. 



The reconnaissance for this scheme of triangula- 

 tion, 1,224 miles in length, was done by a party 

 under Mr. Bowie's direction, in four months and 

 twenty-one days. The scheme consists of 92 pri- 

 mary and 38 secondary stations. 



From Fort Worth to the Pecos River the land 

 is rolling and very similar to that along the 98th 

 meridian in Texas. From the Pecos River west- 

 ward to the Pacific coast the country is moun- 

 tainous with some peaks as high as 11,000 feet. 



Upon the completion of the reconnaissance in 

 February, 1908, the preparation of the stations for 

 observations was begun at the eastern end of the 

 line. Two seasons of observing have been com- 

 pleted, one of five months and three days, and one 

 of four months and fifteen days; a total of nine 

 months and eighteen days. The work done during 

 those seasons was 72 primary stations occupied 

 and completed, 12 primary azimuths observed and 

 two base lines measured. The bases were about 

 thirteen and fifteen kilometers in length. Six 

 hundred and twenty-three miles of triangulation 

 along the axis of the scheme were completed. The 

 party doing this work was under the direction of 

 Assistant J. S. Hill, except for two months of the 

 first season. 



The residts show that the completed triangula- 

 tion is of a grade equal to that of the best half 

 of the primary triangulation previously done in 

 this country. 



Three fifty-meter nickel-steel (invar) tapes were 

 used for measuring each base, and they gave very 

 satisfactory results. Eight primary bases have 

 been measured with invar tapes by the Coast and 

 Geodetic Survey, during the past four years. 

 These tapes hold their lengths well between stand- 

 ardizations. As a result of the use in the field. 



