34 CHANDLER AND McLEOD ON THE 



APPENDIX. 



The Longitude of Oobourg, Ontario. 



By Professor Gr. H. Chandler, M.A. 



The following transit observations wore made in September, 1883, at Oobourg, Ontario (Latitude 

 43° 57') for the purpose of determining the longitude of that place. Simultaneous observations were 

 made by Prof. C. H. McLeod at Toronto. 



The Transit Instrument used was a portable one made by Messrs. Troughton & Simms, 

 and now the property of the Dominion Government. The transit bears the mark F.O. 1. The 

 approximate focal length of the object-glass is 29 inches, its diameter 2.5 inches. The value of one 

 division of the level is 0'. 198. The pivots were found to be cylindrical, and the radius of the clamp 

 end pivot to be 0.14 of a level division smaller than the other. The equatoreal distances of the mean 

 wire from the seveial wires of the reticule were determined from 24 complete transits to be as 

 follows ; — 



From I. + 19.109 "| 

 II. + 9 628 I 

 " III. — 0.012 [-Clamp East. 



IV. 

 Y. 



— 9.672 



— 19.054 J 



The collimation error was made as small as possible by observation of a distant mark. 



The Pier — It was found that the only available pier for the transit consisted of a barrel of sand, 

 the upper part of the barrel having only a few days previously been filled with mortar, which had not 

 yet hardened. The transit was placed in position a few hours before the commencement of the 

 observations, but proved to be so unsteady that the observations of the first night are entirely 

 worthless ; the longitude determination thus depending on the observations of two nights only. 



The Sidereal Chronometer. — This was Wm. Bond & Son's 332, which breaks circuit at the even 

 seconds and at the 59th second of each minute. The observations were made by eye and ear, the 

 break circuit attachment being used only to tr.ansmit the chronometei' beats to Toronto. 



Time Exchanges were made between Cobourg and Toronto each night. The beats of the Cobourg 

 chronometer were recorded on the Toronto chronograph, and return signals of mean time were sent 

 from Toronto, coincidences with the Cobourg chronometer being recorded by me. The transmission 

 time, however, was not determined, owing to an oversight at Toi'onto on the second and third nights 

 of the time exchange, in not comparing the mean time clock with the sedereal clock used in 

 obsei'ving. 



The Stars observed were selected from the Berliner Astronomische Jahrbuch for 1883. 



Level Errors. — In nearly all cases four settings of the level were made after each transit. 

 From the level errors thus obtained, and the corresponding times as co-ordinates, a free-hand curve 

 was sketched, and from this curve interpolated values for the correction of the times of transits were 

 derived. These values are given in the following tables. 



