470 Scientific Intelligence. 



exchange. The growth in the National Zoological Park is noted 

 in particular and also the results obtained in the Astrophysical 

 Observatory by Mr. C. G. Abbott, the Aid in charge. Professor 

 Langley states that the work of the last year "has resulted in 

 the discovery and determination of position of 500 new absorp- 

 tion lines, so that we have now over 700 new lines of well-deter- 

 rnined positions, and we may be said now to know, by the aid of 

 the bolometer and the labors of the observatory, more lines in 

 this invisible spectrum than were known in the visible one up to 

 the great research of Kirchhoff and Bansen, which opened the era 

 of modern spectrum analysis. Moreover, these lines, the exact- 

 ness of whose determination has now reached a surprising degree 

 of perfection through the recent improvements in the delicacy as 

 well as the precision of both bolometer and galvanometer, and 

 through other improvements in the apparatus (improvements due 

 principally to the present Aid acting in charge), depend not only 

 on the instruments, but on the labors of those who have used 

 them, the comparator measurements alone having included, as 

 stated in the body of the report, about 44,000 separate observa- 

 tions. 



" A great deal of other work has been done at the observatory, 

 but nothing which in importance and present and prospective 

 interest compares with this main research in the infra-red spec- 

 trum, which is now known throughout nearly the whole of the 

 invisible portion of the solar energy, and extends through a range 

 of wave lengths considerably over twelve times that known to Sir 

 Isaac Newton, the present exact kuowledge of this region being 

 due not exclusively, but it may properly be said principally, to 

 the labors of this observatory. 



" I call attention in this connection to the interesting remarks 

 made in the report to the effect that very marked changes of 

 absorption have been observed at various parts of the inira-red 

 spectrum. In one part of the invisible region a decrease in 

 absorption, amounting to nearly half the total, took place in 

 February, and this abnormal state continued until May, when 

 the usual condition gradually returned. As this change is found 

 to occur yearly at about the same period, the idea presents itself 

 that the growth of vegetation, so rapid in these months, may 

 abstract from the air large quantities of vapor active in absorp- 

 tion at this point in the spectrum, but this interesting possibility 

 has not yet, it will be understood, been fully verified." 



The second part of the volume, pp. 101-696, contains a series 

 of well-selected papers on important topics, many of them not 

 readily accessible in the original, so that their republication here 

 will be a great convenience to many readers. 



2. Report of the IT, S. National Museum under the direction 

 of the Smithsonian Institution for the year ending June SO, 1898. 

 Pp. xviii, 1270; plates 1-36. 'Washington, 1900. — This volume 

 contains the report by the Director, Mr. Charles D. Walcott, on 

 the condition and progress of the United States National Museum 



