24 REPORT OF THE SECRETARY. 



by night and by day, and the normal and febrile states were studied 

 both when food was administered and when withheld. The result of 

 this was to show that there are two sources of animal heat, one from the 

 stored-np materials of the body, and the other from the food, the first 

 being - the one manifested in fever. 



The results of the whole investigation are summed up in eleven con- 

 clusions which are given in the abstract referred to. 



The publication of recent investigations of the motion of the moon * 

 has rendered a re-discussion of the ancient solar eclipses desirable. 

 This work has been commenced under the auspices of this Institution 

 by Mr. D. P. Todd, M. A., Assistant Nautical Almanac Office. Hansen's, 

 tables of both the sun and moon are employed, the latter being corrected 

 from the results of Professor Newcoinb's researches. So far as the work 

 has now progressed, the computations relate to seven eclipses — those 

 of Thales, at Larissa, of Bnnius, of Agathocles, at Stiklastad, and the 

 two eclipses of the thirteenth century which have been discussed by 

 Celoria, of Milan. The adopted value of the secular acceleration hav- 

 ing been deduced from entirely independent data, it is hoped that this 

 investigation will throw new light on the interpretation of the ancient 

 eclipses, and point toward the true value of the secular acceleration 

 which ought to be adopted in the construction of new tables of the moon. 

 The progress of this investigation will be much facilitated by the new 

 tables of eclipses, t now in press ; and it is proposed to extend the original 

 scope of the research to include a large number of supposed ancient 

 ecliptic dates. 



LABORATORY. 



The original act of Congress calls for a laboratory as one of the ele- 

 mentary features of the Institution, and an establishment of this kind 

 has always been maintained, with a greater or less degree of efficiency. 



In consequence of the limited appropriations by Congress for the 

 maintenance of the National Museum, it has for several years been im- 

 possible to secure the services of a mineralogist. Arrangements have 

 been made, however, for such an officer ; the laboratory has been put in 

 thorough order; additional fittings have been introduced, necessary for 

 its efficiency, and a complete stock of chemicals and other materials 

 procured. It is now in proper condition for the prosecution of investi- 

 gations requiring chemical and mechanical appliances. 



The principal work of the laboratory at present is examining min- 

 erals sent to the Institution for that purpose from various parts of the 

 country, very few days passing without the reception of one or more par- 

 cels, many of them from members of Congress, requiring consideration. 

 The Institution does not undertake to make quantitative analyses, ex- 



' Researches on the Motion of the Moon. By Simon Newcomb, Professor U. S. Navy- 

 Washington Observations for 1W75, Appendix II. 



t Tables of Eclipses, from B. C. 700 to A. D. 2300. By Simon Newcomb, Snperin- 

 tendent Nautical Almanac. Washington, lH7i>. 



