390 



NATURE 



[3far. 14, 1872 



framework; so that by "Diagrams of Forces" the con- 

 ditions of stability of loaded structures, and the form and 

 tensions of suspension bridges, could at once be deter- 

 mined, by measurement of these diagrams or by calcula- 

 tion from them. Of the variety of text-books on the sub- 

 ject of mechanics, the teacher should reject books that 

 profess to be adapted for examinations, as well as those 

 which contain gross errors on the laws of friction, or on 

 the inertia of matter and the laws of motion, or on the 

 subject of dynamical units and should select from those 

 which are not liable to such objections. 



Competitive examinations may be useful if they are 

 made tests of thorough knowledge ; but too often they 

 injure the student who is preparing for them by narrowing 

 his mind, and create a class of dabblers in science, and 

 are worthless for the purpose for which they are intended. 

 Test examinations given to a class on the subject of their 

 lectures are the best tests of the knowledge and progress 

 of the student. 



In teaching the laws of equilibrium of liquids and of 

 gases, the same method must be followed as in te iching 

 the laws of equilibrium and of motion of sjlids ; 

 and in addition to lectures and ordinary teaching 

 students should have the opportunity of making experi- 

 ments and measurements in these subjects in a physical 

 laboratory. Some knowledge of other kindred sciences 

 is necessary before a student can be said to have an in- 

 telligent knowledge of the principles of mechanical science. 

 Accurate investigation and experiment show that near the 

 melting and the boiling points the special properties and 

 lav.'s of solids or of liquids are no longer true, and Dr. 

 Andrews has pointed out the existence of a border-land 

 between the liquid and the gaseous states, and has shown 

 that there is no breach of continuity between them. 

 Taking a model, of which three rectangular edges shall 

 represent the pressure, volume, and temperature, the 

 upper surface will represent the state of the substance, 

 and will explain in what way it is possible to pass from 

 the liquid to the gas without change of state or any sudden 

 change of volume. The ease with which we can conceive 

 of the state of a gas under different circumstances, when 

 we have such a model before us, shows the importance of 

 employing figures and models to give a boy clear ideas of 

 the propositions of mechanics. 



Regarding Mechanics in its wider sense as the Science 

 of Energy, there arc three great principles — the Conser- 

 vation, the Transformation, and the Dissipation of Energy, 

 which have been established, and these principles are 

 illustrated in the conversion of water into steam, in wind- 

 ing up a watch, in the diffusion of gases, in the conduc- 

 tion of heat, in the friction of the tides on the earth, and 

 in the rushing of water down a mountain side. This 

 latter source of energy has been employed in piercing the 

 Mont Cenis tunnel. 



The accuracy of the calculations by which the axes 

 of the two tunnels on opposite sides agreed so completely 

 with one another shows the importance of accurate 

 measurement, and of the correct application of theoretical 

 principles to practice. 



These principles of energy tell us that in raising the 

 waters of the ocean to the mountain tops, as much energy 

 must be expended as can be expended by those waters in 

 their return to the ocean, and the atmosphere, acted upon 

 by the solar heat, is the vast air-engine by which these 

 changes are accomplished. 



NOTES 



At the last meetiiifj of the Royal Society the names of the 

 candidates for election into the Society were read, in accordance 

 with the statutes, as follows : — Andrew Leith Adams, Surgeon- 

 ^lajor; WiUiam Grylls Adams, M.A. ; William Aitken, M.D. ; 



;■ Alexander Armstrong, K.C.B., M.D.; Edward Middleton 



Barry, R.A.; John Beddoe,' B. A., M.D. ; Henry Bowman 

 Brady, F.L.S.; Frederick Joseph Bramwell, C.E. ; James Brun- 

 lees, C.E. ; Edwin KilwickCalver, Capt. R.N.; Alexander Carte, 

 M.A., M.D.; William Chimrao, Coinmander R.N.; Prof. 

 Arthur Herbert Chiu-ch, M.A. ; Fredk. LeGros Clark, M.R.C.S.; 

 Prof John Cleland, M.D. ; Herbert Davies, M.D. ; Henry 

 Dircks, F. C. S. ; August Dupre, Ph.D.; Michael Foster, jun., 

 M.A., M.D. ; Peter Le Neve Foster, M.A. ; Wilson Fox, 

 M.D. ; Arthur Gamgee, M.D. ; Prof Thomas Minchin 

 Goodeve, M.A. ; Townshend M. Hall, F.G.S. ; Edmund 

 Thomas Higgins, M.R.C.S. fRev. Thomas Hincks, B.A. ; Rev. 

 A. Hume, LL.D. ; Henry Hyde, Lieut. -Col. R.E. ; Prof 

 William Stanley Jevons, M.A. ; Edmund Charles Johnson, 

 F.R.G.S. ; George Johnson, M.D. ; Prof Thomas Rupert Jones ; 

 John Leckenby, F.G.S. ; Clements R. Markham, Sec. Geog. 

 Soc. ; William Mayes, Staff-Comm. R.N. ; Edmund James 

 Mills, D.Sc. ; Thomas George Montgomerie, Major R.E. ; 

 Robert Stirling Newall, F.R. A.S. ; Edward Latham Ormcrod, 

 M.D. ; Francis Polkinghorne Pascoe, F. L. S. ; Prof. Oliver 

 Pemberton ; Rev. Stephen Joseph Perry ; John Arthur Phil- 

 lips, F. C. S. ; Bedford Clapperton T. Pirn, Captain R.N. ; 

 William Overend Priestley, M.D.; Charles Bland RadclilTe, 

 M.D. ; Edward John Routh, M.A.; George West Royston- 

 Pigott, M.D.; William Westcott Rundell ; William James Rus- 

 sell, Ph.D.; Osbert Salvin, M.A. ; Harry Govier Seeley, F.L.S.; 

 AlfredR. C. Selwyn(Geol. Survey, Canada); PcterSquire, F.L.S. ; 

 George James Symons, V.P. Met. Soc; Edwin T. Truman, 

 M.R.C.S.; Wildman Whitehouse, C.E.; Plenry Woodward, 

 F.G.S.; Archibald Henry Plantagenet Stuart Worlley, Lieut- 

 Col. 



The Earl of Lonsdale, whose death is recorded this week, 

 was the father of the Royal Society, his election having taken 

 place sixty-two years ago, in 1810. This honour now devolves on 

 Sir Henry Holland, elected in 1S15. 



The death is announced, on the 3rd inst., of Dr. A. B. 

 Gr.anville, F.R.S., at the age of 88. He was one of the 

 oldest Fellows of the Royal Society, having been elected in 

 1S17, and was member of a large number of foreign learned 

 societies. 



We are very glad to be able to state that intelligence has just 

 been received from Prof Huxley that his health has already 

 been greatly renovated by the pure air of Upper Egypt. He 

 wrote from Thebes, and was then contemplating a visit to 

 Assouan, from which he would probably have returned to 

 Thebes before this. 



Sir William Thomson has accepted the office of President 

 of the Geological Society of Glasgow. 



The Radcliffe Travelling Fellowship at Oxford has been 

 aw.arded to Mr. F. H. Champneys, B.A. of Br.isenose College. 

 This Fellowship is of the annual value of 200.' , and tenable 

 for three years, provided the Fellow does not spend more than 

 eighteen months within the United Kingdom. 



The President of the Quekett Microscopical Club will hold a 

 sotrA; on Friday evening, March 15, at University College. 



Dr. Liebreich, the eminent ophthalmist, of St. Thomas's 

 Hospital, delivered a lecture at the Royal Institution on Friday 

 evening last, on certain faults of vision, with special reference to 

 Turner and Mulready. The later "aberrations" of Turner's 

 style he attributed to a physical change in the refractive power of 

 the eye, by which illuminated points were converted into illu- 

 minated lines. The change of manner in Mulready's later pic- 

 tures he accounted for, in like manner, by increasing yello.v 

 degeneration of the crystalline lens. We hope in a future num- 

 ber to give a report of tlie lecture. 



