88 POPULAR SCIENCE MONTHLY. 



36-inch telescope during 1888-90. His faithful and artistic drawings of 

 Jupiter have no equal. 



He was in charge of the very successful expedition sent by the Lick 

 Observatory to Bartlett Springs, Cal., to observe the total solar eclipse 

 of January 1, 1889. 



Professor Keeler resigned from the Lick Observatory staff on June 

 1, 1891, to succeed Professor Langley as director of the Allegheny Ob- 

 servatory, and professor of astrophysics in the Western University of 

 Pennsylvania. The Allegheny Observatory has perhaps the poorest loca- 

 tion of any observatory in this country for spectroscopic work. But in 

 spite of this disadvantage Heeler's investigations continued and pro- 

 moted the splendid reputation established for the observatory by his 

 predecessor. He comprehended the possibilities and limitations of his 

 situation and his means, and adapted himself to them. His spectro- 

 scopic researches were largely confined to the orange, yellow and green 

 regions of the spectrum, since these would be less strongly affected by 

 the smoky sky for which that vicinity is famous. 



The Allegheny spectroscope, designed and constructed soon after 

 his acceptance of the position, contained several valuable improve- 

 ments. The use of three simple prisms in its dispersive train was a de- 

 parture which has been followed with great advantage in many later 

 instruments. With this instrument he made an extensive investigation 

 of the Orion Nebula and the stars immersed in it, establishing the fact 

 that the nebula and the stars are closely related in physical condition.* 

 His beautiful observations of Saturn's rings, proving that they are a 

 cluster of meteorites — myriads of little moons — have never been sur- 

 passed in interest in the entire astronomical field. These observations 

 are so well known to every one interested in astronomy that one sen- 

 tence suffices. He proved spectrographically, using the Doppler-Fizeau 

 principle, that every point in the ring system is moving with the velocity 

 which a moon would have if situated at that distance from the planet. 

 Professor Keeler's main piece of work at the Allegheny Observatory, on 

 the spectra of the third (Secchi) type stars, remains unpublished, but 

 the measures and reductions are left in an advanced stage. 



The regents of the University of California appointed Professor 

 Keeler to the position of Director of the Lick Observatory on March 8, 

 1898. The ties which bound him and his family to Allegheny were 

 difficult to sever; but the greater opportunities offered by the instru- 

 ments and the atmospheric conditions at Mt. Hamilton decided him in 

 favor of accepting the appointment. He entered upon his new duties 

 on June 1, 1898. 



Without making any rearrangement of the work of the staff, but 



* Simultaneous observations of the same object made at another observatory led to the same 

 conclusion. 



