186 Miscellanies. 



his enterpiize with great diligence and ingenuity, and has brought his 

 instruments to a degree of perfection, which enables them to sustain 

 a very honorable comparison with the large telescopes imported from 

 abroad. 



In conjunction with Professor Olmsted, we have recently had an 

 opportunity of examining one of his large Reflectors. It is construct- 

 ed after the manner of Herschel's great Telescope, with a single mir- 

 ror, the image being thrown so near to one side of the open end of 

 the tube, that the eye can be applied to it without intercepting any 

 considerable portion of the light. By this arrangement, the light that 

 is lost by a second reflexion, as in the Gregorian Telescope, is sa- 

 ved, and so much is added to the brightness of the image. The tube 

 is of sheet iron ; the focal length is 7 feet, and the aperture 6i inch- 

 es. The mounting is remarkably simple, consisting merely of two 

 upright staves or supports, which meet in an angle at the open end of 

 the tube, while the farther end may rest on a chair, or even on the 

 ground. Its adjustments in altitude and azimuth, are effected by 

 means of two thumb screws, attached to the staves near the top. 



Although the two nights on which my colleague and myself exam- 

 ined the heavenly bodies with this instrument, were not the most suit- 

 able for observation, yet we were both very favorably impressed with 

 the character of the instrument* We viewed the moon, then in quad- 

 rature, with different powers from 40 to 350. The mountain ridges 

 and peaks, the deep craters, the elongated shadows, and the various 

 other objects exhibited to the best telescopes, were seen to great ad- 

 vantage. The double star ^ in Aquarius was distinctly divided ; and, 

 when in the center of the field, the two separate stars were well de- 

 fined. We believe it, however, in the power of the artist to make 

 farther improvements in the quality of his eye glasses, so as to era- 

 brace a larger field of view, with less of chromatic aberration, and 

 also in the delicacy of his horizontal and vertical movements. 



On the whole, we are of opinion that Mr. Holcomb has, under all 

 the circumstances of the case, achieved wonders in this difficult de- 

 partment of the arts ; and we cordially recommend his work to such 

 of our public Institutions as may desire to purchase powerful teles- 

 copes. 



Yale College, August 15, 1834. 



The Committee on Science and the Arts, appointed by the Frank- 

 lin Institute of the State of Pennsylvania for the promotion of the 



