6Q REPORT OF THE SECRETARY. 



II. Accessory apparatus : 



(1) A complete iustrumeut-maker's lathe, -with outfit of tools and chucks. 



(2) A 30-incli hand and power planer for metal work, witli chuck, etc., from 



the Hendley Machine Comjiany. 



(3) A 40-light incandescent dynamo, "with rheostats, etc., from Westing- 



house Electric Company. 



(4) A one-half horse power motor, from Akron Electric Company. 



(5) A one-fourth horse-power water motor and Sturtevant jiressuro fan, with 



accessory apparatus for cooling the air of the Observatory. 

 The total value of the apparatus purchased during the year was about $3,000. 



MINOR WORK OF THE YEAR. 



In addition to Mr. Wadsworth's work with Prof. Michelson in the establishment 

 of the length of the standard meter in terms of tlie wave length of light, at the 

 International Bureau of Weights and Measures, reference to which has already been 

 made, the following special work, which has been done during the year, may be 

 mentioned: 



(1) The preparation of a complete series of line-shaded drawings of the principal 

 pieces of apparatus in the observatory on a scale requisite to show their detailed 

 construction. 



(2) The preparation of a series of enlargements of moon jihotographs from the 

 Kenwood and Lick observatories, photographs. 



(3) Experiments in temperature and radiation work. 



During tlie latter part of the year preliminary experiments were begun and carried 

 on at intervals looking to the systematic preparation for another extended research, 

 which I have proposed to soon begin to determine the physical relation between 

 temperature and radiation. Tlie experiments have mostly. been directed to the 

 establishment of a satisfactory source of temperature and nieaus of measuring the 

 same. The various apparatus, etc., for the prosecution of this work at an early date 

 has either been ordered or already installed. 



(4) Some further attempts have been made at solar pliotography, but, as the 

 experience of last year conclusively showed, the atmospheric conditions here in the 

 city are very unfavorable to any satisfactory work in this direction. 



PERSONNEL. 



The force of the Observatory consists of a Senior assistant, and an iustrument- 

 malvcr, and an assistant instrument-maker. During the past year the Observatory 

 has also had at different times special assistants, among whom I wish to acknowl- 

 edge the assistance of Mr. J. G. Hubbard, to whose photographic skill several 

 improvements of this jiart of the work are due. 



