Aug. 17, 1876] 



NATURE 



331 



copy I have received, and also that the " May, 1875," has a line 

 drawn through it. While on the subject let me add that the 

 Zoological Society itself, in its ''Transactions," sets a bad 

 example in this respect. Each paper bears a date at the foot of 

 its first page, but the date is likely to be misleading in years to 

 come, for it is that of the printing off the sheet — an essentially 

 private matter, with which the public has nothing to do — and 

 not that of the publication. Another F. Z. S. 



Meteor Observations 



A BRIEF summary of the August (Perseid) meteor observa- 

 tions at York may be of interest. 



Watch was kept on the loth, lith, I2th, and 14th. The 

 night of the i ith was very hazy, the nights before the loth cloudy. 

 There was also much moonlight, except on the 14th. Yet, 

 after making all due allowances. Prof. Herschel thinks that this 

 year's shower indicates a minimum ; the last decided minimum 

 being in 1862. 



The hourly number on. the four nights mentioned were, for 

 one observer, 22, 8, 12, 15, respectively. Perseid radiant and 

 sub-radiants gave 18, 6, 9, 7. Thus, as the shower progressed, 

 there was a regular decrease in the number of Perseids. The 

 apparent exception of the loth was due to the haze. Prof. 

 Herschel gives 15-20 as the hourly number in Kent. On the 

 14th half the Perseids came from Mr. Greg's sub-radiant at 

 7 Cassiopeicc. 



In the south large meteors appear to have been scarce. Here 

 eight, brighter than ist mag. stars, were seen. One, a bolide, low 

 down in the N. W. was very fine. A meteor in the south-west, 

 brighter than Jupiter, was observed by Mr. Waller at Birming- 

 ham as a very brilliant object. 



The total number observed at York was 105, and 90 of these 

 were mapped. Of the latter 66 were Perseids, 43 with trains. 

 On the loth five other radiants produced eight meteors out of 

 53; viz., Cygnus, three; Pegasus, two; Polaris, one; Draco 

 (Hercules), one ; and Ursa Major, one. Fifteen meteors on this 

 night were as bright, or brighter, than a i mag. star. Only two of 

 4th mag. brightness were seen, in consequence of the moonlight. 



Of meteors stationary, or nearly so, three were mapped: — A 

 Perseid on the 12th at M 32^ and 5 + 58f, its train lasting ■i\ 

 sees. ; on the 14th a Cygneid at I^ 306° 5 +35°, and an unknown 

 radiant, probably near 5 Vulpeculse, gave the third at M. 

 295° S -J- 28, 



Three meteors unmistakably confirm Mr. Greg's sub-Perseid 

 radiant by 7 Cassiopeia:, whilst several others probably radiate 

 from the same. The radiant, Greg 83, by i? Draconis, gave two 

 meteors on the 12th and one on the 14th. It is put down, how- 

 ever, as lasting only from July 12-31. 



Six Perseids on the loth, and four on other nights, seem pretty 

 clearly to indicate a sub-radiant at M. 50°, 5 + 40°, near a Persei. 

 The rest, as Prof. Herschel also noticed, shot very constantly 

 from the chief radiant, between rj and x Persei. Here, however, 

 rj Persei seemed the most central point. 



York, Aug. 15 J. Edmund Clark 



THE FRENCH ASSOCIATION 



IN addition to the notes already given with regard to 

 the forthcoming meeting of the French Association 

 at Clermont, the following particulars relating to the Puy- 

 de-D6me (furnished by our correspondent there) will 

 doubtless be found interesting : — 



Clermont, Atigust 13 



The Puy-de-D6me is connected with most important 

 scientific events, which render it notable amongst more 

 lofty mountains. 



Pascal, in 1644, then quite a young man, was apprised 

 by Pere Mersenne, the celebrated friend of Descartes, 

 that Torricelli had invented his tube. The then admitted 

 explanation was that nature abhorred a vacuum. 



He entered into a correspondence on the subject with 

 Father Noel, a Jesuit professor of natural philosophy 

 in the College of Clermont. Father Noel contended 

 against the very existence of the vacuum, and asserted that 

 the so-called vacuum was filled by luminous matter enter- 

 ing through the glass. Pascal answered by arguments 

 worthy of his genius, and to be recommended for con- 

 sideration in the discussion about radiometers. He said, 



"As the nature of light is known to neither you nor 

 me, and as it is very likely it will always be so, I see 

 it will be long before your reasoning acquires the force 

 which is necessary to its becoming the source of any 

 conviction." After having uttered this opinion he re- 

 flected more fully upon the subject, and was led to 

 believe that the surplus height of mercury in the tube 

 was equivalent to the weight of the air which could not 

 reach the molecules, being intercepted by the resistance 

 of the glass. This led him to inquire if air-pres- 

 sure was not lessened by taking the Torricellian tube 

 to the top of a mountain. The experiment was made 

 in Paris first on the top of St. Jacques la Boucherie 

 Tower and Notre Dame. As the difference was found 

 to be only a few lines, Pascal sent his brother-in-law, 

 Perrier, who was a counsellor in the Cour-des-Aules 

 at Clermont, to the top of Puy-de-D6me with a Tor- 

 ricellian tube. Clermont was supposed to be at an 

 altitude greater than Paris by 400 toises ; Font-de-l'Arbre 

 is a village in the vicinity of the mountains where car- 

 riages are obliged to stop, at 250 toises from Clermont, and 

 250 toises from the top of the mountain. All these mea- 

 surements are incorrect ; a toise being v<^\ metres, we find 

 the following differences : — Paris, 60 metres, Clermont, 

 407 ; difference, 347 metres, instead of 776, as assumed 

 by Pascal ; Puy-de-D6me, 1,465. Difference between 

 Puy and Clermont = 1,058 metres ; according to Pascal 

 only 952 metres. 



The loss of mercury from Convent des Minimes to the 

 top of Puy was found to be 37^ lines ; at Font-de-l'Arbre 

 a diminution of 14^ Hnes from Minimes. A line is equal 

 to 2j mm. 



Perrier discovered no difference, owing to the wind or 

 state of the atmosphere. Such was not the opinion of 

 Pascal, who discovered that the mercury varies ac- 

 cording to the atmospheric conditions of the air. But 

 Perrier was only an amateur experimentalist, and his spe- 

 cial ideas had little weight with his clever brother-in-law. 



In order to ascertain the fact, continuous observations 

 were made at Clermont, by Perrier, during the years 

 1649, 1650, and 165 1. They were simultaneously made 

 at Paris and at Stockholm, where Descartes was then 

 living at the court of the famous Queen of Sweden. They 

 were continued by Descartes up to the time of his demise. 



It is strange that the Pascal experiments were made 

 the very year when Torricelli died, and the results pub- 

 lished only in 1664, two years after Pascal's death. 



W= 



THE SCIENCE DEGREES OF THE UNI- 

 VERSITY OF LONDON 

 E have received from the Registrar of the University 

 of London a copy of the Report of a Committee, 

 and the new regulations which have been introduced in 

 harmony with that Report, in the examinations for the 

 science degrees. From a perusal of the Report, which 

 we subjoin, all will feel how much is gained by the 

 prompt action of the Senate of the University in so 

 speedily modifying the plan of their examinations in 

 accordance with the experience which they have ob- 

 tained during the last seventeen years. It is not, 

 however, only experience in the examination of science 

 students which has led to the necessity for change, but 

 the stimulus which has been given to the teaching of 

 physics and biology, by the founding of science degrees 

 and otherwise, has so altered the method of teaching these 

 subjects that what was expected to be known formerly 

 is quite different from that taught by the most able ex- 

 ponents of the subjects at the present time. 



No change has been made in the Examination for the 

 Doctor of Science degree, which we regret, because in the 

 Report of the Duke of Devonshire's Committee on Scien- 

 tific Education great stress was laid on the importance of 

 obtaining an original thesis from each candidate. 



The Report of the Committee runs as follows :— 



