28 EEPOET OF THE SECRETARY. 



by niglit and by day, and the normal and febrile states were stndied 

 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-up 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 Newcomb's researches. So far as the work 

 has now progressed, the comi:)utations relate to seven eclipses — those 

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

 two eclipses of the thirteenth centurj' which have been discussed by 

 Celoria, of Milan. The adoi)ted 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 i)rogress 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 tliis 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 IsTational Museum, it has for several years been im- 

 possible to secure tlie services of a mineralogist. Arrangements have 

 been made, however, for such an officer 5 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 woi'k of the laboratory at present is examining min- 

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

 (jountry, very few days j^assing 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 Moou. By Simon Newcomb, Professor U. S. Navy. 

 Washin,!^ton Observations for 1875, Appendix II. 



tTables of Eclii)ses, from B. C. 700 to A. D. 2300. By Simon Newcomb, Superin- 

 tendent Nautical Aknauac. Washington, 1879. 



