May 2, 1878] 



NATURE 



25 



eight feet C of musicians, the other, being an octave lower in 

 pitch, adds an octave to the intervals obtained from the first 

 fundamental ; thus, the third with the first fundamental becomes 

 the tenth with the sub- fundamental. The horizontal box is 

 furnished with a set of reeds giving all the intervals up to the 

 twelfth, including the unison. The horizontal reeds are changed 

 for the production of the different figures, the fundamental reed 

 being retained. 



A free space of half an inch was allowed between the supply 

 pipe and the reed box, so as to afford a cushion of air capable 

 of )delding to the elasticity of the tongue. The supply pipe is 

 contracted at its termination to about one-third the size of the 

 hole in the reed box through which the wind enters. 



The apparatus is used as follows : — The base board being 

 firmly clamped to a rigid table, one of the fundamental reeds is 

 clamped in front of the box B : another reed, giving the desired 

 interval, is similarly clamped to the box B ; an elastic tube, 

 about half an inch in diameter, is attached at one end to the 

 pipe C, and at the other to an acoustic bellows. A fine 

 pencil of light is now thrown on the mirror E, which is then 

 adjusted by rotation of the box A until the light strikes the 

 mirror of the vertical reed, from whence it is reflected on to a 

 screen of tracing paper placed a short distance away ; a con- 

 denser, interposed between the lantern and the mirror E, 

 focuses the spot of light on the screen. On the bellows being 

 put in motion the figure appears, and can be brought to a perfect 

 stand in any phase of development, looped or cusped, by careful 

 manipulation of one or other of the cocks. The entire apparatus 

 should be as rigid as possible, and free from any vibration other 

 than that produced by the tongues of the reeds, and also that the 

 wind supply should be perfectly steady. 



THE PARIS OBSERVATORY 



A' 



S we announced some time ago, an important step has been 

 ^ taken for the reorganisation of the Paris Observatory. A 

 decree of the President of the French Republic has appointed ten 

 members of the new council of the Observatory, in pursuance of 

 the provisions of the organic decree we referred to two months 

 ago. The principal object of this new institution being to 

 connect the observatory with the several large French administra- 

 tions, three Government departments have sent two delegates each. 

 The War Office is represented by Col. Laussedat, the director of 

 the balloon service, and Commander Perrier, the chief of the 

 Ordnance Survey ; the Minister of Marine by two rear-admirals, 

 one of them, M. Jurier de la Graviere, being a member of the 

 late Council ; the other is M. Clouet ; the department of agri- 

 culture by M. Tisserand, Director of the National School of 

 Agriculture, and M. Herve Mangon, a member of the Institute 

 and president of the Meteorological Society of France. The 

 Academy of Sciences is represented by four members, carefully 

 selected, viz., M. Dumas, the perpetual secretary, who is to be 

 appointed president, and M. Liouville, the celebrated geometer, 

 and two astronomers, M. Faye and M. Mouchea, both of them 

 members of the Section of Astronomy. It must be noted that the 

 Council of the Observatory, although vested with the right to 

 present to the minister two candidates for the directorship of 

 that establishment, are not to interfere with the solution of 

 technical questions. A special council composed of all the 

 astronomers en titre of the Observatory, are to meet once a 

 month to solve them with the director of the Observatory. The 

 first meeting of the Council of the Observatory took place on 

 April 24, M. Dumas being in the chair. The members had 

 been summoned in order to send to the Ministry a list of two 

 candidates for the direction rendered vacant by the demise of 

 M. Leverrier. The meeting was very short, and the members 

 having been unable to agree, it was postponed to the 26th, when M. 

 Faye wished to deliberate on the vexed question of the separation 

 of meteorology and astronomy. This, however, was not allowed, 

 when M, Faye protested and declared that he would bring the 

 question before the Academy of Sciences at its next meeting, on 

 April 29. After several scrutinies the Council decided to send 

 in the names of MM. Mouchez, Loewy, and Tisserand as their 

 nominees for the directorship of the Observatory, the last two 

 having obtained an equal number of votes. Such was the 

 result of the deliberations of the Observatory Council, which on 

 the whole seem to have been conducted with becoming dignity. 

 At Monday's sitting of the Academy, M. Dumas simply read 

 M. Bardoux's letter, and summoned a meeting for to-day of a 

 Committee of the Academy composed of all the sections in the 



mathematical sciences. A list of candidates will then be formed 

 for proposal to the whole Academy, which will vote its candidates 

 on May 5. It then remains with the Government to choose 

 between the candidates proposed by the Council and Academy. 

 M. Faye made no protest at the Academy meeting on Monday, 

 though, our correspondent writes, he was expected to speak on 

 the subject in a secret committee which met after the meeting of 

 the Academy. We trust that throughout these important steps 

 for the appointment of a successor to Leverrier all personal 

 feelings will be suppressed, and the interests of the Observatory 

 and of science alone considered. 



SOCIETIES AND ACADEMIES 

 London 



Royal Societ}', February 7. — "On the Diurnal Range of 

 the Magnetic Declination as recorded at the Trevandrum Obser- 

 vatory," by Balfour Stewart, LL.D., F.R.S., Professor of Natu- 

 ral Philosophy at Owens College, Manchester. 



The Observatory at Trevandrum was supported by His 

 Highness the Rajah of Travancore, and its director was Mr. J. 

 A. Broun, F.R.S., who has recently published the first volume of 

 the results of his labours, giving the individual observations of 

 magnetic declination, and deducing from them conclusions of 

 great scientific value. 



Amongst the other results published by Mr. Broun, are the 

 diurnal ranges of the magnetic declination at Trevandrum for 

 each civil day in the eleven years, 1854 to 1864. 



In one respect the treatment of the declination observations 

 at Trevandrum differs from that pursued at the Kew Observa- 

 tory, inasmuch as in the former place, where disturbances are 

 little felt, the diurnal ranges are from all the observations. 



Variadons cf Long Period. 



In order to investigate the long-period variation of the Tre- 

 vandrum declination-range, I have treated these observations pre- 

 cisely in the way in which the Kew declination-ranges were treated 

 {Proc. Roy. Soc., March 22, 1877). By this method proportional 

 values of the declination-range at Trevandrum have been obtained 

 corresponding to weekly points for each year, and it is believed 

 that these values are freed from any recognised inequality de- 

 pending either on the month of the year or on the relative posi- 

 tion of the sun and moon. If this method should be found to 

 furnish nearly the same results in the case of two observatories 

 so widely apart as Kew and Trevandrum, and with such marked 

 differences in the annual variation of the declination-range, we 

 may conclude that this separation of inequalities has been suc- 

 cessfully accomplished. 



The proportional numbers have'next been dealt with precisely 

 in the way in which the corresponding numbers were dealt with 

 in the case of the Kew Observatory, that is to say, a set of nine- 

 monthly values of declination-range have been obtained corre- 

 sponding to similar nine-monthly values of spotted solar area. 



The results of this treatment are exhibited in the diagram 

 which accompanies this paper. 



In Fig. I we have a curve representing the nine-monthly 

 values of spotted area. 



In Fig. 2 we have the . Kew and in Fig. 3 the Trevandrum 

 declination curve represented by nine-monthly values of the pro- 

 portional numbers. 



In Fig. 4 we have a curve representing the mean between the 

 proportional numbers of Kew and those of Trevandrum. 



From these figures it will be seen that a lagging behind the 

 sun is a feature both of the Kew and the Trevandrum curves, 

 while generally the prominent points in the Kew and Trevandrum 

 curves agree well together in point of time. 



On the whole it would appear that by taking the mean of the 

 proportional numbers for the two stations, we get a ^curve that 

 represents the solar curve better than one derived from a single 

 station. 



The whole period compared together represents both foe the 

 solar curve (Fig. i) and the mean curve (Fig. 4), a series of 

 three smaller periods, one extending from B to C and embracing 

 the maximum ; another extending from C to c, and a third from 

 c to e ; and this is as far as the observations common to both 

 stations allow us to go in point of time. 



It may be of interest to compare, by means of the tables, the 

 period between the solar minimum of 1855 and that of 1867, with 

 the period between the corresponding declination-range minima. 

 The first of these declination minima occurred at Trevandrum (the 



