386 ANNUAL OF SCIENTIFIC DISCOVERY. 



originality. They are surprised and delighted at the simplicity with 

 which all danger of error from eccentricity or flexure is avoided, as a 

 partial equivalent for which , it may be important not to overlook any 

 short lateral motion of the pivot of the telescope in its socket. In its 

 present form, the apparatus must be considered to be purely differential, 

 and to depend upon other fundamental observations for the absolute 

 determination of the length of its arc. With this condition, the meas- 

 urement of differences of declination may extend to the degrees, and 

 perhaps much further, without any loss of accuracy. The principal 

 feature which characterizes this apparatus, and distinguishes it from all 

 others, consists in its admitting of the observation of ten different hor- 

 izontal wires during a single transit ; and these observations are made 

 with great facility, without mental tension, and so close to the meridian 

 as to involve no difficulty in their reduction to the meridian. 



By an additional piece of mechanism for some observations, these 

 may be conducted with unsurpassed rapidity, and sufficient exactness, 

 without risk of confusion or any perplexity of thought on the part of 

 the observer. 



Finally, the committee are not aware that the history of astronomi- 

 cal science exhibits a more astonishing instance of great results pro- 

 duced with what would seem to be wholly inadequate means. With 

 the ordinary tools of a common mechanic, and with insignificant pecu- 

 niary outlay, an isolated individual has aspired to rival the highest 

 efforts of the most richly endowed institutions, upon which sovereigns 

 and governments have showered their inexhaustible patronage, and his 

 aspirations have been crowned with success. The committee are per- 

 suaded that under more propitious circumstances, and with more gen- 

 erous opportunities, Prof. Mitchel's plans of apparatus will lead to still 

 more admirable results, and contribute yet further to the advancement 

 of astronomical science. 



At the conclusion of the report, Prof. Bache remarked, that the value 

 of this report was enhanced by the cool, investigating character of the 

 members of the committee, and the practical and theoretical knowledge 

 which they had brought to their task. The circumstances attending 

 the reception of the description of Prof. Mitchel's invention at the New 

 Haven meeting further increased its value. It was not surprising that 

 those versed in the methods of astronomical observation in established 

 use should be sceptical in regard to the performance of an apparatus 

 avowedly constructed with imperfect means, and startled when its 

 results were stated as vying with those of perfect instruments imported 

 or made at a great cost. The committee has carefully and with great 

 minuteness investigated the whole apparatus, its action and its results ; 

 and they unanimously report that they are satisfied that the claims 

 set up to this method as a marked improvement are real. It goes out, 

 then, with the stamp of this Association ; it has passed a critical or- 

 deal, and stands by its merits as one of the most remarkable steps ever 

 made in our country in the progress of astronomical observation. 



The instrument and apparatus of Prof. Mitchel are of too complex a 

 character to admit of a description in this place. It suffices to say, 

 however, that by their aid the astronomer can now accomplish more 



