Allegheny Observatory,
Allegheny, Pennsylvania.
Sept 26 1894

My Dear Mr. Lumsden,

      I am greatly obliged to you for your kindness in sending me the bound volume containing the earlier transactions of the society. It makes my set complete, and I can have the later volumes bound to match.

      As for the article I thank you for reminding me of it. I was away during the summer and on returning found a spell of clear weather, something so unusual that I have put all my time into observing. What I had in mind was a method of changing the chromatic aberration of a visual telescope so as to adapt it to photographic work with the spectroscope at H-gamma, but I find it is not such a simple matter as I had supposed. Something of the kind seems to be absolutely necessary if we are to use our great refractors for measuring motions of stars in the line of sight, I will let you know later how I come on.

Yours very sincerely

J. E. Keeler.

The article referred to here appeared in the 1894 volume of the Society's Transactions (starting on page 90).