March 14, 1902.] 



SCIENCE. 



421 



centers of reduction to the two higher 

 planes, and thence by interpolation to 

 points over the station; the second, from 

 the station pressure to the pressures on 

 the two other planes directly. This agree- 

 ment, therefore, unites the entire data in 

 a homogeneous system, and it becomes the 

 basis for future substantial scientific dis- 

 cussions in many meteorological problems. 

 We can now deal quite confidently with 

 hundredths of an inch of pressure. 



A full report on this subject will appear 

 in the Annual Report, Chief of Weather 

 Bureau, Vol. II., 1900-1901, and will con- 

 tain the following sets of charts for each 

 month and for the year, iJ,„ . t^. e^. and 

 the relative humidity on the sea level 

 plane, B^ .t^ . e^ on the 3,500-foot plane, 

 B„.t^. e„ on the 10,000-foot plane, 130 in 

 all; also charts of gradients in latitude, in 

 longitude and in altitude, as well as charts 

 for reducing selected hours of observation 

 to the mean of twenty-four hourly obser- 

 vations. With these data a newly opened 

 station can by a little computation be put 

 on a better basis regarding its normals 

 than would be given by at least ten years 

 of regular observations. A summary table 

 contains the above list of normals for 265 

 stations besides the original data for the 

 station B„ .t . e., and will be a valuable 

 source of reference for numerous ques- 

 tions in meteorology. 



The reduction tables for pressure con- 

 sist of three different sets: (1) The gen- 

 eral logarithmic tables computed for every 

 100 feet up to 10,000 and for every 10 de- 

 grees from — 40° to + 100°; (2) the sta^ 

 tion tables for publication, containing the 

 following corrections for each of our three 

 planes of reference, sea-level, 3,500-foot 

 and 10,000-foot, namely, the Laplacean 

 free dry air correction, the humidity cor- 

 rection, the correction for the plateau 

 effect and the occasional residual correc- 

 tion, also the two arguments t surface tem- 



perature and & the mean column tempera- 

 ture. Diagrams have been constructed to 

 show the relations between t and e, and 

 they form a most instructive analysis of 

 the plateau temperature problem, showing 

 that each district has local characteristics 

 of its own; (3) the station tables are com- 

 piled from the forms (2), and they are ex- 

 panded for the arguments surface t and 

 surface B, so that there shall be no inter- 

 polation along the temperature argument 

 in order to obtain the nearest hundredth 

 of an inch, 0.010. The body of the table 

 gives the reduced pressure on its plane, 

 and not the correction to the actual pres- 

 sure, which must be added to it to produce 

 the reduced pressure, as is customary in 

 such tables. There remains only a very 

 simple interpolation for the intervals of a 

 tenth of an inch of pressure to the re- 

 quired hundredth of an inch. It is thus 

 an easy matter to enter the three tables in 

 succession with the same arguments, sur- 

 face (B.t), and find B, .B^.B^. These 

 data will enable us to construct three sets 

 of isobars at each hour of observation, 

 showing three plane sections through the 

 atmosphere, and these will probably prove 

 to be of value in the forecasts of the 

 weather conditions. The sea-level reduc- 

 tions went into operation on January 1, 

 1902, as stated, but some more work is re- 

 quired to furnish the stations the necessary 

 tables of group (3), the two preceding 

 groups being completed. 



Feank H. Bigblow. 

 Weather Bueeau. 



SCIENTIPIG BOOKS. 

 Memorial Lectures delivered hefore the Chem- 

 ical Society of London, 189S-1900. London, 

 Gviruey and Jackson, Paternoster Kow. 

 1901. 8vo. 



This volume contains the lectures com- 

 memorating deceased honorary and foreign 

 members of the Chemical Society of London, 

 delivered during the eight years designated in 



