1002.] SNYDER — A NEW METHOD OF TRANSITING STARS. 205 



strument for its usual work however accurate. Excepting in the 

 unnecessary weight of the parts and general coarseness of the 

 mechanism, the transiter as now constructed fairly meets all the de- 

 mands originally set and besides introduces some new conven- 

 iences. Although it is not the intention at present to give a de- 

 tailed description of the transiter, it may be allowable briefly to 

 mention several of its advantages : 



Regulation of the bisection of a star is easy and definite. A 

 record is made but once for each revolution of the micrometer, 

 and records will be increased in frequency only as special work 

 demands. A predetermined schedule of recording can be deter- 

 mined for any given run of the micrometer. Back lash of the 

 screw on reversal of motion may be completely eliminated by 

 the adjustment of the electrical contacts. The whole transiter 

 may be balanced symmetrically on the instrument, and thus 

 changes in the instrumental constants avoided. Instantaneous re- 

 versal of the motion of the micrometer permits of many conven- 

 iences as to method of work. In determinations of time and 

 longitude the tendency has of late been to reverse the transit in- 

 strument during the passage of each star, and thus to eliminate a 

 series of errors and facilitate reductions. The transiter by its 

 ability to reverse motion instantly, and even automatically, lends 

 itself readily to this method of work. 



From the beginning of 190 1, when it was completed, until the 

 present the transiter has been the subject of many tests and of 

 some improvements, and for a year or more it is hoped it may be 

 destined to progressive change. It is now mounted on the four- 

 inch meridian circle, for which it is expected a suitable place may 

 be found at the Suburban Photographic Station of the Observatory, 

 when this Station shall have been definitely located, but only after 

 the completion of the present series of experiments with the transi- 

 ter, and the determination of the latitude and longitude of the City 

 Station of the Observatory. 



Personal equation in all its variations remains a much more 

 serious factor than many painstaking astronomers, who have not 

 sufficiently practiced their accuracy even against a simple personal 

 equation machine, are willing to admit. It is then gratifying to 

 find that Professor Langley^ has recently been willing to propose 



1 Prof. S. P. Langley presided at the meeting, and had at a recent meeting of 

 the American Astronomical and x\strophysical Society described his new and 

 very ingenious method of obviating personal equation in any time observation. 



