For many years I have had almost daily to reply to inquiries respecting the best method of manipulating with various kinds of Spectroscopes.

It had been suggested to me long since, by our highest authority on the subject, that I should write a small work giving the required information. For reasons which will be understood by my friends, I had a great objection to issue such a work, and trusted it would be done by some of the leading scientific men who have worked in this direction. But recently the inquiries for information have been more and more numerous, and I am compelled, both to save my own time and to assist my numerous correspondents, to attempt to supply what appears to be an evident want.

Mr. Proctor's admirable little Manual on the Work of the Spectroscope will be found invaluable by those who do not wish to incur the expense of Roscoe's or Schellen's works on Spectrum Analysis. But Mr. Proctor states that it did not enter into his plans to give detailed instructions for the use of the various kinds of Spectroscopic Apparatus.

I have, therefore, endeavoured to supply such information in the following Pamphlet. The fact that a list of prices is appended of the various Instruments which are described, will not, I hope, be considered to detract from its value. My extensive correspondence leads me to conclude that such information is exceedingly welcome to all those who think of making any experiments for themselves.