Intelligence and Miscellaneous Articles, 155 



appear in the second edition. "We have already mentioned two ; a 

 third occurs in the second paragraph of Art. 61, p. 39, where 

 the word " plane" is dropped out. Moreover the substance of the 

 paragraph is not strictly correct, even when the printer's error has 

 been set right. 



Catalogue of Stars observed at the United-States Naval Observatory 

 during the years 1845 to 1871. Prepared for publication by Pro- 

 fessor M. Yaenall, U.S.N, Washington, 1873. 



This Catalogue, which forms Appendix III. of the Washington 

 Observations for 1871, contains the places in right ascension and 

 declination of 10,658 stars observed during a period of more than 

 a quarter of a century with the transit instrument, meridian circle, 

 prime vertical, mural circle, and equatorial of the observatory. The 

 preliminary matter treats principally of the methods employed for 

 the reduction, throughout the Catalogue, to the Besselian epoch 

 1860*0, when the sun's longitude was 280°. The Catalogue gives : — 

 the designations or numbers of the stars observed as they stand in 

 the catalogues named, with the magnitudes, the mean right ascen- 

 sion 1860*0 with the mean year of observation; the number of ob- 

 servations of each star with its annual precession in 1860 ; the 

 mean declination, mean year of observation, number of observations, 

 and annual precession in 1860. 



The Catalogue contains a large number of small stars which 

 were observed in consequence of Mr. James Ferguson, who had 

 charge of the equatorial, requiring many for comparison with 

 the objects observed by him. Mr. Ferguson having observed the 

 stars of the Pleiades with the equatorial, and those in Prsesepe 

 having been observed with the same "instrument by Professor 

 Hall, many in both clusters were reobserved with the transit 

 instrument and mural circle. The resulting right ascensions and 

 declinations are inserted separately from those determined with the 

 equatorial. We cordially recommend this Catalogue to the atten- 

 tion of amateurs, and the more so as so many telescopes of large 

 aperture are now in active work in this country. 



XX. Intelligence and Miscellaneous Articles, 



ON A NEW DETERMINATION OF THE MECHANICAL EQUIVALENT 

 OF HEAT. BY H. SERRANO Y FATIGATI. 



nPHE mechanical equivalent of heat had not, until now, been deter- 

 -*• mined by the relation which subsists between the work expended 

 to turn the disk of a Eamsden electrical machine and the electro- 

 static decompositions produced. The following are, in brief, the 

 process I have employed to resolve the problem and the results 

 which I have obtained. 



To turn the disk and measure the work, I wound round the 

 handle of the disk of a Eamsden machine two strings passing over 

 two pulleys and carrying each a weight at its extremity — the one 



