242 



PROCEEDINGS OF THE AMERICAN ACADEMY 



TARLi: I.— Continued. 



No. 



Date. 



1879-80. 

 *21! Oct. 4 



22 

 *23 



♦24 



25 



*26 



1880. 

 June 9 



June 13 



June 16 



July 28 

 July 29 



Object. 



a Aurigte 

 Moon 



a Bootis 

 a Bootis 



a Bootis 

 Moon 



a Scorpii 

 a Lyrse 



27 July 29 i a .\(iuilse 



28 July 29 a Aijuilae 



29 July 30 



•30 July 30 



12h. 



to 

 131i. 



9h. 27m. 



to 

 lOh. 16m. 

 9;i. 20m. 



to 

 9h. 50m. 



8h. 35m. 



to 

 91i. 30m. 



9h. 



to 



9h. 25m. 



a. Scorpii 8h. 51m. 



I to 

 a Aquilse lOh. 10m. 



o Lyrae 



Inst. 



12in. 

 12iu. 



12-in. 

 12in. 



12-in. 

 12in. 



11-in. 



28-in. 



28-in. 

 11-in. 

 11 ill. 



11 in. 

 11-in. 



11-in 



llemarks. 



Q rays focused on the slit. 



A good picture. 



During the winter of '70 and '80 a new 

 worm whtel \va.s made by Alvan Clark 

 & !»ou.s tor the driving-clock, to replace 

 the old oue, which was liniiid to be 

 slightly eccentric. Dr. Draper moved 

 to the country in June, ISSO, and occu- 

 pied a few days in getting it into place. 

 it answered extrciiiely well, and the 

 clock wa.s now sensibly perfect. 



6 rays were focu.sed on the slit The 

 night was dear, but the picture is 

 faint 



At the end of 30 m. the exposure wjis 

 stopped by clouds. The night was so 

 windy that the dome was blown around, 

 and the force of the wind overcame the 

 strength of the declination damp, so 

 that the telescope moved in declination, 

 and made two impressions of the spec- 

 trum on the plate. Notwithstanding 

 this, it is a good picture, extending 

 from above IL to below !•', showing a 

 large number of lines, and a bright 

 band on the more refrangible side of H. 

 The (} rays were focu.sed on the slit 



Moon over-exposed, and a Bootis faint. 

 The night was damp and not clear ; 

 bluish fog. 



At this time Dr. Draper exchanged the 

 12-iiu'h for the ll-iiuli with photo- 

 graphic corrector referred to above. 

 The new instrument was received July 

 9th. but was not fully ready for work 

 until near the end of the month. The 

 28-iiich reflector had been resilvered in 

 the mean time, so that the siiecti-oscope 

 could be u.sed eitlier with it or with the 

 refractor. 



Sky clouded so there was no impression 

 on the plate. 



Only about fifteen minutes of this ex- 

 posure were clear, but it is a strong 

 picture The clouds cleari> 1 away, and 

 the night became remarkably clear. 



Fine picture. 



At the end of 3Si m., the star having 

 moved to the west of the meridian, a 

 slip in declination took pliice, owing to 

 taking up the slack. This changed 

 the position of the star on the plate, 

 and made a second impression of 

 4| m. 



Atmosphere wa." hazy, and the first 16 

 m. of the exposure a Scorpii was very 

 faint on account of clouds It had a 

 good exposure of 30 m.. After 9 o'clock 

 the night was clear a .Soorpii"s spec- 

 trum was faint, a. AquiKip's very strong. 



Before making this exposure on a Lyne, 

 moved the slit of the spectro.scope out- 

 side the focus of the telesrope 413 

 divisions of the micrometer, so a.s to 

 widen the spectrum. After an expos- 

 ure of 7 m shifted the star on the 

 plate, and then gave it the remaining 

 time, 28^ rn.. but the two pictures are 

 nearly superposed. 



