574 



NATURE 



\Sept 26, 1878 



the sand-pendulum, being careful that when the board is 

 slid under the stationary pendulum the point of the 

 funnel goes precisely over the centre line L M (Fig. 9) of 

 the curve. 



Now draw the point of the funnel aside to a distance 

 from the line L M equal to one-half of A B, or, what is the 

 same, from 5 to 5' of Fig. 9. Pour sand in the funnel, and 

 let the bob go. At the moment the point of the funnel is 

 over L, slide the board along so that when the point of 

 the funnel comes the third time to the line L M, it is at 

 the end M of this line. This you may not succeed in 

 doing at first, but after several trials you will succeed, 

 and then you will have an answer from the pendulum as 

 to the kind of motion it has, for you will see the sand 

 from the swinging pendulum strewed precisely over the 

 curve you placed under it. Thus you have conclusively 

 proved that the apparent motion of the conical pendulum, 

 along the line A B, is exactly like the swinging motion of 

 an ordinary pendulum. 



As it is difficult to start the board with a unifonn 

 motion at the very moment the pendulum is over the line 

 L M, it may be as well to tack a piece of paper on the 

 board with no curve drawn on it, and then practise till 

 you succeed in sliding the board under the pendulum, 

 through the distance L M, in exactly the time that it 

 takes the pendulum to make two swings. Now, if you 

 have been careful to have had the swing of your pendu- 

 lum just equal to A B, or from 5 to 5' on the drawing of 

 the curve, you will have made a curve in sand which is 

 precisely like the curve you have drawn ; for, if you trace 

 the sand-curve on the paper by carefully drawing through 

 it the sharp point of a pencil, and then place this trace 

 against a window-pane with the drawing of the curve, 

 Fig. 6, directly over it, you will see that one curve lies 

 directly over the other throughout all their lengths. 



This curve, which we have made from the circle in 

 Fig. 6, and have traced in sand by the pendulum, is 

 called the curve 0/ signs, or the sinusoid. It is so called 

 because it is formed by stretching the circumference of a 

 circle out into a line and then dividing this line, L M of 

 Fig. 6, into any number of equal parts. From the points 

 of these divisions i, 2, 3, 4, 5, &c., of L M, we erect per- 

 pendiculars 2 2', 3 3', 4 4', 5 5', &c., equal to the lines a 2, 

 ^3, ^4, d$, &c., in the circle. These lines in the circle 

 are called sines, so when we join the ends of these lines, 

 erected to the straightened circumference by a curve, we 

 form the curve of sines, or the sinusoid. 



The sinusoid occurs often during the study of natural 

 philosophy. We may meet with it again in our book on 

 the nature of light, and it certainly will occur in our book 

 on heat. 



{To be continued.) 



NOTES 



Up to the present time the ignorance of those who did not 

 know that the Archbishop of Canterbury was a degree-giving 

 body was pardonable. It is so no longer. A serious alteration 

 in the arrangements of these diplomas is now announced. Arch- 

 bishop Tait, while he intends to dispense doctorates as before at 

 his will and pleasure, has determined that his degree of M.A. is 

 from December next to be a matter of examination. The stan- 

 dard is to be that of " honour examinations in the Universities." 

 There is to be due choice of subjects, among which, however, 

 Greek and Latin are not to be compulsory, though English 

 literature is. To qualify for examination, formal testimonials 

 required for University matriculation, with the addition of a 

 certificate from the Bishop of the diocese whence the candidates 

 come, are required. As the Daily News puts it, "the Arch- 

 bishop has evidently determined to make himself into a univer- 

 sity with all the paraphernalia which the modern conception of 

 such a body requires." Both the London Examining Board 

 (commonly called the London University) and Owens College 



are to be congratulated on the pubUcity now given to this singu- 

 lar system of granting degrees. The London Examining Body 

 is not a teaching body, neither is the Archbishop, but the Arch- 

 bishop is a university, therefore the London University system 

 is perfect, and all methods of education whatever may be dis- 

 regarded so that a standard of instruction is reached. Owens 

 College as a teaching centre which has won its way to general 

 esteem and confidence, may now bide its time, for this last 

 grotesque thing calling itself a university will either make the 

 power of granting degrees, and degrees themselves ridiculous, 

 or direct attention to the whole subject. 



Although the Paris meeting of the Iron and Steel Institute 

 has not called for any lengthy notice at our hands, there are 

 passages in Dr. Siemens' admirable address to which we cannot 

 too strongly draw attention, and which we are anxious to place 

 on record in our columns. He remarked that " Whilst the 

 English, to realise a novel proposition, make bold attempts, not 

 always carefully matured beforehand, the French systematically 

 study a question in all its aspects, and fortify their views by 

 careful inquiry into the experience obtained elsewhere, before 

 they commence operations which are then carried out with all 

 the economical ^and other advantages resulting from such an 

 exhaustive preliminary inquiry. If we seek a cause for the 

 remarkable aptitude of adapting means to special ends, to which 

 I have referred, we shall probably find it in the advantages 

 P'rance and other continental countries have enjoyed for at least 

 a generation of a more extended technical education than we 

 could boast of, and :of the personal influence which has been 

 exercised by a line of scientific writers and experimentalists, of 

 whom I shall only mention here such honoured names as those 

 of Reaumur, Ebelmen, Regnault, Pouillet, Peclet, Thomas, and 

 Le Chatelier, as belonging to the past, and of Deville, Griiner, 

 Lan, Laurens, Jordan, Fremy, and Dumas, who are fortunately 

 still among us. It is chiefly to such men as these that France 

 owes her admirable system of education, which enables her 

 to place her metallurgical establishments under the gui- 

 dance of men who are scientifically qualified for the 

 discharge of their respective duties, and for the attainment 

 of practical results which may well excite our admiration." 

 The organisation of the Ecole Centrale, the creation of M. 

 Dumas, recommends itself, as it may well do, to Dr. Siemens, 

 and he points out that the only establishment in Great Britain 

 comparable with the £cole Centrale as regards metallurgy is our 

 School of Mines, which, "if it were installed in a capacious 

 building, and had other branches of knowledge added to its cur- 

 riculum, might easily, under the guidance of such men as Percy, 

 Smyth, Frankland, and Huxley, be developed into an institu- 

 tion which would give rise to beneficial results difficult to over- 

 estimate." Had Dr. Siemens been speaking in England he would 

 doubtless have added that this was the distinct recommendation 

 made by the Duke of Devonshire's Commission after a long 

 inquiry. The Government has not yet acted upon this recom- 

 mendation, and the result is that students of the School of 

 Mines have to get their mathematics when and how they can ; 

 they form no part of the curriculum. Many may think that 

 such schools in France are too heavily weighted with mathematics, 

 but to omit the subject altogether is to court Scylla with a ven- 

 geance. Why should not each student of the School of Mines 

 receive, as at the Ecole Centrale, a three years' course of general 

 scientific education, including the higher branches of mathe- 

 matics, as well as physical science, pure and applied chemistry, 

 geology, mechanics, metallurgy, and mineralogy. 



Mr. H. Forbes, F.L.S., is about to leave this country to 

 investigate the fauna and flora of Celebes, Borneo, and adjacent 

 islands. He proposes to devote five or six years to the work. 



Vesuvius is now giving some very definite signs of an 

 eruption. 



