REPORT OF THE SECRETARY. 15 



University of Cincinnati. Professor Stone has chosen for this work a 

 number of assistants, and will proceed with the reduction and discussion 

 of the observations made on this comet at its several returns as rapidly 

 as his other labors will permit. 



The perturbations of the first order have been calculated, and the zero 

 stars used in determining the place of the comet at the time of its last 

 return in 1871 have been re-observed with the Washington meridian 

 circle. An accurate determination of the orbit traversed by this comet 

 in 1871, as based on the corrected position of these stars, has been in 

 part completed. 



In this connection it may be interesting to state that of the one hundred 

 and forty* asteroids discovered during this century, forty-two were first 

 observed by American astronomers. It is not enough, however, that 

 these bodies should be noted as planets, and their j)ositions marked in 

 the heavens for a given epoch ; it is also necessary that their orbits 

 should be accurately determined, and an ephemeris of each of them cal- 

 culated by which its place can be ascertained at any future time. This 

 work, however, is one, as it were, of approximation, and must be con- 

 tinued through a series of revolutions of each planet. In regard to the 

 asteroids discovered in Europe, the investigation of them is under the 

 charge of European astronomers ; while for the investigation of those 

 discovered in America, Congress has made an appropriation for the last 

 three years, to be expended under the direction of Professor Coffin, 

 director of the American Nautical Almanac. 



Efficiency of steam-heaters. — Another investigation, at the partial ex- 

 pense of the Smithsonian Institution, has beeu undertaken under the 

 direction of General W. B. Franklin, late of the United States Army, 

 at the Colt's Fire- Arms Manufacturing Company, Hartford, Conn., by 

 Mr. C. B. Bichards, of which the following is an account: 



The experiments which are proposed will be in continuation of two 

 series already made, to ascertain the relative efficiency of the different 

 kinds of steam-heaters used for warming buildings, and to determine 

 also the laws of their operation. The first series related to what are 

 known as " direct radiators,'"' and in these the heaters were exposed in a 

 large room whose temperature could be changed and regulated as desired. 

 In the second series the heaters were of the kind called " indirect radi- 

 ators," and were inclosed in a flue through which currents of air were 

 passed. The initial and final temperatures, the barometric pressure, 

 and the moisture of the air were noted, and the quantity passed through 

 the flue was measured by a Casella meter. 



In both series the pressure of the steam was measured by an accurate 

 mercury column, and its temperature was noted, while the heating effect 

 of the heater was calculated from data obtained by collecting, cooliug, 

 and weighing the water of condensation obtained from the steam which 

 was passed through the heater. 



* Since the above was written two additional asteroids have been discovered. 



