THE INCORPORATORS 179 



In 1858 experiments were begun in astronomical photography, 

 which were carried on so successfully, that on the occasion of the 

 total solar eclipse in 1860, observed in Labrador with the first 

 telescope constructed especially for photographic purposes, a 

 distinct difference was shown in the character of the limbs of the 

 sun and the moon. In 1861 Rutherfurd constructed "a Cas- 

 segrainian reflecting telescope with silvered glass mirror, having 

 13 inches aperture and 8 feet focus," but the necessity for fre- 

 quent resilvering and the tremors caused by the location in the 

 city interfering with good work, the reflector was abandoned 

 after a short trial. 



Mr. Rutherfurd's first astronomical paper was published in 

 1862. In this he confirmed Clark's discovery of the companion 

 of Sirius, having found the object with his n-inch telescope. 

 The next season he made seventy-nine measures of position-angle, 

 and thirty-eight of distance. These observations, added to those 

 made at Cambridge and at Pulkowa, gave the principal basis of 

 knowledge of this newly-found body for two years. 



In 1863 Mr. Rutherfurd published in the American Journal 

 of Science his second scientific paper entitled " Astronomical Ob- 

 servations with the Spectroscope," in which he gives the result of 

 his observations and measurement of the spectra not only of the 

 sun, moon, Jupiter and Mars, but also for seventeen stars. He 

 continued his observations of the companion of Sirius, and also 

 published a paper in 1863 on " Observations on Stellar Spectra." 

 Not long afterward he began to employ photography in these 

 investigations, and obtained a fine representation of the solar 

 spectrum which he exhibited to the National Academy of 

 Sciences in 1864. He further improved his apparatus by the 

 use of extraordinarily delicate diffraction gratings, the secret of 

 making which he learned for himself, and with these obtained 

 results in the study of solar and stellar light that were unequalled 

 until Draper entered upon the same field some years later. 



Even more interesting and important are the results which 

 Rutherfurd obtained in the construction of telescopic object- 

 glasses for photographing celestial bodies. After much thought 



