JXJNE 17, 1910] 



SCIENCE 



959 



The original use of the name as a class desig- 

 nation in contradistinction from Eeptilia has 

 not been noticed, however. Baur only traced 

 it back to 1822. It will interest herpetolo- 

 gists, therefore, to learn that it was formally 

 used as early as 1806. 



In 1806 Latreille published the first volume 

 of his work entitled " Genera Crustaceorum 

 et Insectorum " and in his introduction (I., 

 p. 2-3) enumerated the twelve classes of the 

 animal kingdom then recognized by him." 

 The third and fourth classes were vertebrates 

 with a single ventricle (" cor uniloculare, san- 

 guine frigido"), the third class (" Classis 

 III". Eeptilia, Eeptiles ") having lungs only 

 (" pulmones ") and the fourth class (" Classis 

 IV. Amphibia, Amphibies ") having both 

 lungs and gills ("pulmones et branchiae"). 



Of course these definitions do not represent 

 modern ideas of the really distinctive char- 

 acters of the classes in question, but neither 

 does any old definition of any class embody 

 modern concepts of the group intended to be 

 diagnosed. 



Theo. Gill 



SOCIETIES AND ACADEMIES 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 681st meeting was held on May 21, 1910, 

 President Woodward in the chair. Two papers 

 were read. 



Methods of Measuring the Modulus of Bending 

 of Flat Metal Springs: Dr. R. S. Woodwakd, 

 of the Carnegie Institution of Washington. 

 This paper explained three methods for meas- 

 uring the modulus in question. The first two 

 methods assume that the spring is clamped hori- 

 zontally and rigidly at one end and permitted to 

 assume the shape due to its own weight. This 

 shape is defined by the following differential 

 equation : 



(Ff/d(r- zp — aiT cos f, 



wherein ^ is the inclination of the neutral surface 

 of the spring at any point, <7 is the quotient of 

 the distance of this point from the free end of the 

 spring by its whole length, and a is a number 



° In 1804 Latreille adopted the classification of 

 Brongniart (1799) in which the amphibians were 

 ranked as an order of reptiles (" Ordre IV., 

 Batraciens, Batrachii"). 



involving the modulus desired. The paper shows 

 how to integrate this equation so as to give i/', 

 cos ^ and sin ^ simultaneously in power series 

 of 0-, and hence how to get the coordinates of any 

 point in the elastic curve. When the latter are 

 observed for the free end of the spring two equa- 

 tions result from which a and hence the modulus 

 of bending may be found. Another equation from 

 which a may be found results from equating the 

 internal work of bending the spring to the ex- 

 ternal work done by gravity on the spring. 



The third method of finding this modulus re- 

 quires the application of a simple device which 

 will bend a spring into a circular curve. The 

 modulus of bending is then equal to the product 

 of the applied bending moment by the radius of 

 tnis curve. 

 Solar Radiation Intensities at Washington, D. G.: 



Professor Herbert H. Kimball, of the U. S. 



Weather Bureau. 



The results given are based on more than 7,350 

 separate determinations of the intensity of solar 

 radiation made by the author at the Central 

 Ofiiee of the Weather Bureau with an Angstrom 

 pyrheliometer during the five years ending April 

 30, 1910. The observations were distributed over 

 272 half-day periods, or rather more than one 

 half day to each week, and the radiation intensi- 

 ties are expressed in gram calories per minute 

 per square centimeter of normal surface according 

 to the Angstrom standard of pyrheliometry. 



The maximum and the inean rates of radiation 

 with a sky free from clouds were determined 

 hourly or half hourly for a day in each month 

 with average declination of the sun for the month. 

 From these rates the daily and the monthly totals 

 received on a surface normal to the solar rays, 

 and also on a horizontal surface, were determined, 

 first, on the supposition that the sky was free 

 from clouds, and second, by taking account of the 

 recorded duration of sunshine. 



The maximum observed intensity of solar radi- 

 ation, 1.44 calories, occurred in April, and the 

 maximum for December, 1.32 calories, is only 

 8 per cent. less. The greatest monthly noon 

 average, 1.28, occurs in February and the Decem- 

 ber average, 1.15, is only 10 per cent. less. The 

 greatest daily total of radiation received on a 

 normal surface, 971 calories, occurs in July, the 

 corresponding December total being 60 per cent, 

 as great. The greatest daily total for a hori- 

 zontal surface, 653 calories, also occurs in July, 

 and the corresponding total for December is only 

 30 per cent, as great. 



