tion in schools, and with improvement in methods and results there comes a demand for the special cultivation of teachers, by means of institutes and normal schools.
This complex machinery of education must be thoroughly understood by every efficient teacher in its principles and practical working, and Prof. Phelps's book has been prepared to facilitate this special professional culture. It is written with the warmth of a man who is in earnest, and with the clearness of one who understands his subject. Unsettled questions and difficulties in education are recognized, with judicious suggestions, as in the following passage:
"The question as to what shall be taught in our common schools is yet to receive a definite solution. Next in importance to right methods of teaching ranks the subject-matter of teaching. 'What knowledge is of most worth? What branches are the most useful, first for discipline, and second for use or particular application?' Upon this subject we have no settled policy. As a consequence, many things inferior usurp the place of those of superior worth. The dry details of so-called geography, the abstract definitions, rules, and formulas of grammar, the comparatively valueless signs and symbols of algebraic notation, consume a vast amount of the time that should be devoted to the study of the earth, its climate and productions in their relations to man, and the course of human history; of the English language, as a means of communication, and of the living sciences which lie at the basis of all the arts and industries of life. But it is futile to attempt a revolution in subject-matters while teachers, their attainments, and methods of work, are so inadequate to the public needs. It is idle to talk of the necessity of the elements of physics and chemistry, botany and physiology, natural history and agriculture, so long as we have neither the knowledge nor the skill requisite to their proper treatment. Of what value would these sciences be to the people When mechanically memorized from the printed page, as are most of the subjects now in our common-school curriculum? To be of use, either for discipline or application, they must be properly taught by observation, experiment, and demonstration. In short, their objects must be seen, handled, analyzed, compared, and classified. These practical sciences must be investigated by methods and processes analogous to those by which they have been themselves developed, and thus far perfected. Can our children be expected to grope their way to these natural processes in spite of their teachers? or, must the latter first be made capable of leading the way, inspiring the young by the fullness of their learning, and the skill of their methods? Until our children and youth learn the right use of their own powers, it is in vain to expect that they can master the powers of Nature, or accomplish any other important result."
The Uranian and Neptunian Systems, investigated with the 26-inch Equatorial OF the United States Naval Observatory. By Simon Newcomb, LL. D., Professor United States Navy. Washington Observations for 1873. Appendix I. Government Printing-Office, 1875, pp. 72, 4to.
This pamphlet, separately printed, contains the first published discussion of work done by the 26-inch Clark refractor of the Naval Observatory. What this work was, and how great necessity existed for its prosecution, may be gathered from the first two paragraphs of the memoir:
"The remoteness of the two outer planets of our system renders the accurate investigation of their satellites a task of great difficulty. This is strongly evinced by the great discordances between the conclusions respecting the masses of those planets which have been reached by various observers. Thus, in the case of Uranus, Von Asten, the latest investigator, cites a number of determinations of the mass from recent observations, which range between 1⁄1987X and 1⁄27616 [of the sun's mass], so that the largest result is nearly half as large again as the smallest. Even different results, obtained by the same observer under slightly different circumstances, were surprisingly discordant. The best determination was that of Struve; but even here there was a difference of four per cent, between the results from the two [brighter] satellites. In the case of Neptune, discordances of the same kind showed themselves; Struve's mass being greater than that of Bond by one-third.
"For these and other reasons, when the 26-inch equatorial, with an object-glass nearly perfect in figure, was mounted at the Naval Observatory, the observation of the satellites of the outer planets, with a view of determining not only the elements of their orbits, but more especially the masses of the planets, was made the first great work of the instrument. Entertaining the opinion that, in the present state of astronomy, it was better to do one thing well than many things indifferently, the minor arrangements of the instrument were all made subservient to the end in view, and no other serious work of a dissimilar character was attempted during the continuance of the observations."
It is well known that the two brighter satellites of Uranus, viz., Oberon and Titania, are quite faint objects even in the large 15-inch telescopes of Harvard College and of Pulkova, but the two interior satellites, Ariel and Umbriel, are incompara-
