190 



NATURE 



\yuly 9, 1874 



A MONUMENT TO JEREMIAH HORROCKS 



AT the last meeting of the Royal Astronomical So- 

 ciety, Prof. Adams said that he had been requested 

 to call the attention of the Society to a petition which was 

 about to be presented to Dean Stanley. It would speak 

 for itself, and he would therefore read it to the meeting. 

 It ran thus : — 



To the Very Reverend the Dean of Westminster. 



Reverend Sir, 



It appears to us that the approaching transit of 

 Venus offers a fitting occasion for the erection of a me- 

 morial to Jeremiah Horrocks, curate of Hoole, in Lan- 

 cashire, to whom the science of astronomy is indebted 

 for the earliest observation of Venus upon the sun's disc. 

 He predicted, by his own calculations, the transit of the 

 year 1639, which he and his friend Crabtrce had the 

 exclusive privilege of witnessing. The labours of Hor- 

 rocks in connection with this memorable occurrence, as 

 well as the originality of his views on other astronomical 

 subjects, have, by the unanimous consent of scientific 

 men, assigned to him a high place in the roll of illus- 

 trious astronomers who adorned Europe in the seven- 

 teenth century. 



We therefore venture to request your permission to 

 place in Westminster Abbey a tablet or some other me- 

 morial of Jeremiah Horrocks. 



We have the honour to be, 

 Reverend Sir, 



Your obedient Servants, 



(Signed) by the Astronomer- Royal, the President of the 

 Royal Astronomical Society, and a number of the most 

 distinguished Fellows of the Society. 



Prof Adams remarked that he need not say anything 

 further to recommend the signature of the memorial to 

 the Fellows of the Society. It was perfectly impossible 

 to estimate too highly the credit due to Horrocks, espe- 

 cially when his age and opportunities were taken into 

 account. Not merely had he been successful in observ- 

 ing the transit of 1639, but he had first corrected the 

 tables of Venus, from his own observations, and had 

 thereby rendered his prediction of the transit possible. 

 Had he merely followed the tables which had been pub- 

 lished by Kepler, he could not have predicted the transit, 

 and it would probably have slipped by unobserved. And 

 this was by no means the only astronomical service ren- 

 dered by Horrocks. His discovery of the law of libration 

 of the moon's apogee constituted an important advance 

 in the knowledge of the lunar motions. In fact. Sir 

 Isaac Newton, when nearly half a century afterwards he 

 attempted to explain those motions on mechanical prin- 

 ciples, could not find any more convenient representation 

 of the motion of the moon's apse than that which had 

 been given by Horrocks. He had, therefore, great plea- 

 sure in bringing this petition to the notice of the Fellows 

 of the Society. 



FRENCH PREPARATIONS FOR THE 

 TRANSIT OF VENUS 



AT the meeting of the French Academy of June 29, 

 M. Dumas gave in the Report of the Commis- 

 sion charged with making the necessary preparations for 

 observing the approaching transit of Venus. 



The stations chosen by the commission are Campbell and 

 St. Paul Islands, Houmda, Pekin, Yokohama ami Saigon. 

 Each expedition is under the charge of a chief, the con- 

 duct of the first having been intrasted to M. liouquet de 

 la Grye, the second to M. Mouchcz, the third to M. 

 Andre, the fourth to M. Fleuriel, the fifth to M. Janssen, 

 and the sixth to M. Hcr.iult. The observers altogether 

 number twenty-five, accompanied by twenty-five assis- 

 tants. M. Bouquet de la Grye has already left ; M. 



Fleuriel is on the point of setting out for Pekin. M. 

 Janssen loses no time in leaving for Yokohama, from 

 which he will not return directly to Europe, having under- 

 taken to go to Siam to observe the eclipse which will be 

 visible there. 



As Campbell and St. Paul Islands are perfectly barren, 

 the expeditions destined for them have been specially 

 cared for, being furnished with fuel and provisions for six 

 months. 



A sum of 300,000 francs was allotted by the State for the 

 whole of the expeditions ; but this sum having been 

 found insufficient, the Minister of Marine has abundantly 

 and generously provided for the wants which have been 

 pointed out by the Commission. Indeed, the French 

 Government has acted in the most handsome manner 

 towards the various expeditions, which have been furnished 

 with everything that is in any way necessary. 



As to instruments, besides those which have been 

 specially constructed for the enterprise, the depot of 

 Marine has placed at the disposal of the expeditions a 

 large number of instruments, among which are thirty-one 

 tested chronometers. Four of the expeditions have each 

 received an equatoreal of 8 in. No expedition from any 

 other country, the Report states, will be possessed of in- 

 struments so powerful. Equatoreals of 6 in. have been fur- 

 nished to the six expeditions, and telescopes of the same 

 power as those adopted by the various expeditions of 

 other countries. 



Various photographic apparatus and methods of obser- 

 vation have beer proposed. The Commission has 

 decided in favour of the system of M. Fizeau, who has 

 himself superintended the construction of instruments and 

 initiated the operators in all the practical details which 

 they ought to follow. 



ON VAPORISING METALS BY ELECTRICITY 

 'X'HE following simple results obtained by frictional 

 -'- electricity may be of interest, perhaps too of use 

 in the investigation of certain minerals and the action 

 of intense heat upon them. 



The description of a characteristic experiment is all that 

 will be necessary to explain the process and to show how 

 similar results may be obtained from other substances. 

 A very fine thread of sheet platinum, of about an inch in 

 length, is placed between two microscopic slides of glass, 

 and two pieces of thin sheet copper with rounded ends 

 are placed in contact with the extremities of the platinum, 

 the copper being any convenient length and breadth, so 

 as to extend beyond the glass slides, but not to be as 

 broad ; a charge of electricity from about eight square 

 feet of Leyden jar is passed through the metals ; the 

 effect of the heat from the charge is to vaporise the plati- 

 num, which is instantly condensed in a transparent layer 

 upon the cold glass. The layer can be investigated by 

 a microscope, and employed in various ways to deter- 

 mine the character of the metal and its effect upon 

 reflected or transmitted light. 



Copper, tinfoil, tinfoil amalgamated with mercury, gold 

 and silver, can be used in a similar manner, but they pro- 

 duce layers very dissimilar in appearance. To act upon 

 finely-ground substances, such as vermilion, sulphate of 

 antimony, sulphur, S:c., a line of the powder must be 

 made and the charge be passed through in the same 

 way as through the platinum. 



Part of the vapour escapes from between the slides, but 

 this can easily be condensed upon each of two pieces of 

 glass placed in such a way as to intercept the vapour as 

 it passes from between the two slides ; it is then con- 

 densed in a long but narrow line. The manner in which 

 the glass is affected by the heat, and the concussion pro- 

 duced by the expansion of the vapour, are worthy of notice. 



Considerable difiiculty will be found in vaporising 

 copper, doubtless from its being such an excellent con- 



