86 POPULAR SCIENCE MONTHLY. 



His 'Kecord of Observations made at the Mayport Observatory' con- 

 tains beautiful colored sketches of Jupiter, Saturn, Venus, Mars, the 

 Orion Nebula, of double stars and of 'Scenery on the Moon'; and in 

 addition, data of a numerical character. These early drawings are 

 characterized by the refined taste and skill so well known from his later 

 professional work. 



Keeler entered Johns Hopkins University late in 1877; and, fol- 

 lowing major courses in physics and German, he was graduated with 

 the de°ree of A. B. in 1881. At the end of his freshman year he 

 accompanied Professor Hastings, as a member of Professor Holden's 

 party from the Naval Observatory, to observe the total solar eclipse of 

 July 29, 1878, at Central City, Col. Although his part was the modest 

 one of making a drawing of the corona, his written report on the work 

 is a model scientific paper, and may be read with profit by visual observ- 

 ers of eclipses. 



In the spring of 1881 Professor Langley, desiring an assistant in the 

 Allegheny Observatory, requested the Johns Hopkins University to rec- 

 ommend a suitable man for the place. Keeler was named and accepted 

 the appointment, beginning work at Allegheny several weeks before re- 

 ceiving his degree. I was speaking in June of this year (1900) with one 

 of the physicists who had recommended Keeler for the Allegheny posi- 

 tion, and the subject of this very appointment came up. "I told Pro- 

 fessor Langley," said he, "that one of my strongest reasons for the rec- 

 ommendation is that Keeler doesn't claim to know everything." To 

 the end of his life this charming trait remained unimpaired. It is to 

 Keeler's credit that he largely defrayed his own expenses in college by 

 acting as assistant to some of the lecturers in the experimental courses. 



Professor Langley made his noted expedition to the summit of Mt. 

 Whitney, Cal., in June-September, 1881, to determine the value of the 

 'Solar Constant.' Keeler accompanied the expedition in the capacity 

 of assistant, and carried out his share of the program with skill and 

 efficiency. Eeturning at once to Allegheny, his work until May, 1883, 

 was closely related to the many problems arising from the Mt. Whitney 

 expedition. 



The year 1883-84 was devoted to study and travel abroad. The 

 months of June, July and August, at Heidelberg, were given to the 

 study of light and electricity under Quincke, chemistry under Bunsen, 

 and integral calculus under Fuchs. In the winter semester in Berlin 

 he heard the lectures on physics by Helmholtz and Kayser, on differen- 

 tial equations by Runge and on quarternions by Glan. His main in- 

 vestigation in the physical laboratory was on 'the absorption of radiant 

 heat by carbon dioxide' — a problem suggested no doubt by his Mt. 

 Whitney experiences. 



From June, 1884, to April, 1886, Keeler again served as assistant in 



