The Spectroscope - And Its Work #266175

Spectroscopic Analysis clear and simple for beginners, but at the same time accurate, and as complete as pos sible within so limited a space — following, in this respect, the plan already adopted in my elementary treatises on Astronomy and Physical Geography. In order to make room for subjects properly belonging to Spectroscopy, several subjects which are very fully treated of in large works on the Spectroscope (and indeed in one not containing more letterpress than the present) have been dealt with very briefly. It seems to me that — to mention but one such subject — full accounts of the various contrivances for obtaining in tense heat and light, such as that with which Schellen occupies the first fifty-two pages of his treatise on Spectrum Analysis, are unsuitable even for large works intended for the general student, and are altogether out of place in an elementary treatise, necessarily limited in size. I doubt, indeed, whether anything can be usefully said in textbooks respecting details of the con struction of instruments which the observer (who alone could profit by such explanations) must possess and employ. A few minutes devoted to the examination of the instrument itself will, in such a case, be of more use than many hours' study of textbook explanations. On the other hand, I have endeavoured to give a full account of all the principles on which the application of Spectroscopy depends, as also of all the chief methods of observation and then results. I am greatly indebted to Mr. J. Browning, the emi nent Optician, for the use of many cuts illustrating various forms of Spectroscopes, and their adjuncts.