April 3, 19 13] 



NATURE 



ascertain the yield from an area of about fifty square 

 miles of the northern portion of the watershed. The 

 area in question varies in elevation from 500 to 2060 

 ft. Rain-gauges to the number of forty-six were 

 fixed on this area, being approximately 1 to each 700 

 acres. In the last thirteen years the recorded rain- 

 fall lias averaged 46-34 in. The lowest rainfall of 

 any of the gauges was 34 in., and the highest 61 in. 

 The flows over the measuring weir are recorded on 

 a rotating drum driven by clockwork with cam attach- 

 ment. The highest flood on the drainage area 

 occurred before the building of the weir. It was 

 calculated to have reached a flow of 486 cu. ft. per sec. 

 per 1000 acres from an area of 9321 acres. The mini- 

 mum flow recorded was 0-20 cu. ft. per sec. per 1000 

 acres. Records of evaporation from a w.ater surface 

 6 ft. square showed a variation from 1025 in. in 1907 

 to 19-62 in. in the year 1911. The general result of 

 the measurement of the rainfall and the yield of the 

 river showed that the quantity of water collectable 

 was— on the average of the seven years under con- 

 sideration—equal to 75-2 per cent, of the rainfall. 



Messrs. Longmans, Green and Co. have in pre- 

 paration a series of monographs on physics, which 

 will to some extent follow the lines of their mono- 

 graphs on biochemistry and on inorganic and physical 

 chemistry. The editors of the physical series will be 

 Sir J. J. Thomson, O.M., F.R.S., and Dr. F. Horton, 

 of the Cavendish Laboratory, Cambridge. The first 

 volume in the series will be "Rays of Positive Elec- 

 tricity," by Sir J. J. Thomson. 



Messrs. Henry Sotheran and Co., 140 Strand, and 

 43 Piccadillv, London, have issued part viii., forming 

 part Hi. of the Supplement, of their " Bibliotheca 

 Chemico-Mathematica." The catalogue not only con- 

 tains an unusually complete collection of works on 

 the exact sciences, including many old works of rarity 

 and interest, but also on such kindred subjects as 

 ballooning, horology, and meteorology. The net 

 prices of the volumes are given in every case. 



The classified list of Smithsonian publications, 

 available for distribution on January 1 last, has been 

 published by the Smithsonian Institution of Washing- 

 ton. The institution is able to supply papers only as 

 an aid to the researches or studies in which applicants 

 are especially interested. The papers included in this 

 list are distributed gratis, except as otherwise indi- 

 cated. Of the serial publications of the institution, 

 the volumes of "Contributions to Knowledge" and of 

 "Miscellaneous Collections" are distributed only to 

 public libraries and to learned societies. 



Messrs. J. and A. Churchill announce the follow- 

 ing works for early publication :—" Liquid Air, 

 Oxygen, and Nitrogen," by G. Claude, translated from 

 the French by H. E. P. Cottrell ; "The Examination 

 of Waters and Water Supplies" (second edition), by 

 Dr. J. C. Thresh; "A Laboratory Text-book of Chem- 

 istry," part i., by V. S. Bryant; vol. vii. of the new 

 edition of "Allen's Commercial Organic Analysis," 

 rewritten, under the editorship of W. A. Davis and 

 S. S. Sadtler. 



NO. 2266, VOL. 91] 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences for April: — 

 April 6. 5I1. 33m. Sun eclipsed, invisible at Green- 

 wich. 

 12I1. om. Jupiter at quadrature to the Sun. 



8. s n - 10m. Venus in conjunction with the 



Moon (Venus 4 1' N.). 



9. 22h. 41m. Saturn in conjunction with the 



Moon (Saturn 6° 22' S.). 

 20-22. Maximum of Lyrid meteors. 

 24. 14I1. om. Venus in inferior conjunction 



with the Sun. 

 ,, 17I1. om. Mercury at greatest elongation 



W. of the Sun.' 



26. 2h. 13m. Jupiter in conjunction with the 



Moon (Jupiter 5° 9' N.). 



27. i6h. 24m. Uranus in conjunction with the 



Moon (Uranus 3 52' X.). 

 2ih. om. Uranus at quadrature to the 

 Sun. 



The Radial Velocity of a Persei.— Hnatek having 

 recently published the conclusion that the radial_ velo- 

 city of a Persei varies in a period of 4-1 days, it ap- 

 peared desirable to Mr. J. H. Pitman (Lick Observa- 

 tory Bulletin 224) to undertake a comprehensive 

 treatment of the subject based on all available observa- 

 tions. In addition to the many results already pub- 

 lished by various authorities, the chief being the long 

 series by Goos and Hnatek, the author has employed 

 ten hitherto unpublished determinations. Six of these 

 made during October, 1912, give a mean velocity of 

 -2-49 + 0-42 km. per second. The discussion leads to 

 the conclusion that the radial velocity of a Persei 

 must be either constant or only minutely variable in 

 a period still undetermined. 



The Smithsonian Astrophysical Observatory.— 

 The report on the operations of the Smithsonian Astro- 

 phvsical Observatory for the year ending June 30, 

 1912, has been received. The director, Mr. C. G. 

 Abbot, is to be congratulated on the success at last 

 attending his persistent efforts to obtain a grant from 

 Congress. This enabled simultaneous spectrobojo- 

 metric determinations of the solar constant of radia- 

 tion to be made at Bassour, Algeria, by the director, 

 and at Mount Wilson by Assistant Aldrich, on twenty- 

 nine davs during August-November, 191 1. The 

 observations have not vet been completely reduced, 

 but so far as the" first half of September 

 the values obtained at Bassour agree with those pre- 

 viously determined at Washington and Mount Whit- 

 ney iii indicating a local condition at Mount Wilson 

 tending to make the results too small by about 2 per 

 cent. 



Further, it appears that high solar constant values 

 obtained at Bassour coincide with high values at 

 Mount Wilson, and vice versd. This relation is ex- 

 hibited in two diagrams; in the first the curves 

 obtained by plotting the successive values at the two 

 stations show a rough parallelism; in the second the 

 simultaneous values are plotted, and instead of group- 

 ing round a centre thev are seen to be strung out 

 along a line. It is further stated that a solar varia- 

 tion of 1 4 per cent, was indicated at both stations. 

 The importance of setting at rest the question of the 

 variability of this fundamental factor in meteorology 

 is thoroughly realised by the energetic director, who 

 returned to "Bassour last May to extend his former 

 observations. Mr. Fowle had already commenced 

 work at Mount Wilson in April. It is confidently 

 anticipated that the combined results will be decisive. 

 The solar constant work has received help from valu- 

 able results obtained by Mr. Fowle in continuat-on 



