32 



NATURE 



[November 2, 191 1 



and to an average increase of more than 4 lb. in 

 weight. At the age of sixteen the boys are ij inches 

 taller and 8 lb. heavier than a generation ago. The 

 improvement is less marked at seventeen and eighteen years 

 of age, and disappears in those who stay until nineteen. 

 These calculations are based on more than 6000 measure- 

 ments. This remarkable change probably has many causes, 

 chief among them being the steady diminution or post- 

 ponement of early infectious disease in childhood, due to 

 the progressive operation of the Public Health .Act of 1875, 

 A second factor of equal, if not greater, importance has 

 been the changed attitude towards athletics and physical 

 exercise, particularly during the younger ages, that prevails 

 throughout the school to-day. Other causes of the general 

 improvement in physique are the better housing, the in- 

 creased knowledge and better use of foods, and the greater 

 insight into the meaning of parental responsibility as re- 

 gards health, which are certainly affecting a considerable 

 number of homes at the present day. In order to test the 

 question as to whether the free scholars — two-thirds of 

 whom come from the elementary schools — are of inferior 

 physique to their companions, comparisons, based on 

 250 cases, were made between the two at successive 

 years of life, and it is found that, though the " free 

 scholar " is slightly smaller at eleven, twelve, and thirteen, 

 yet by the age of fourteen he has equalled his companions 

 in height, and in some cases surpassed them. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Microscopical Society, October 18.— Mr. H. C. 

 Pliinmer, F.R.S., president, in the chair. — T. W. 

 Butcher : Structural details of Coscinodiscus asterom- 

 phaliis. A paper describing the primary areolations with 

 the secondary and tertiary markings, illustrated by a series 

 of lantern-slides made from photomicrographs obtained at 

 a magnification of iioo. In addition, slides were shown 

 demonstrating a fine siliceous network, or veil, lying upon 

 the outer surface of the valve, and others in series, from 

 photomicrographs taken, at 5 or 6 consecutive foci, of the 

 he.xagonal cell layer with its " ringed " openings of Mor- 

 land, to prove that these openings are clear and not 

 obstructed by the finely perforated membrane recently re- 

 ported by Mr. Nelson Qourn. Roy. Micro. Soc, October, 

 1910). The membrane being non-existent, its value as a 

 test for a high-power lens is ni7.— Rev. Hilderic Friend : 

 New British enchytrajids. Enchytraeiis minimus, Bret., 

 was described in the Rev. Suisse de Zoologie in 1899. 

 Michaelson in Das Tierreich, 1900, suggested that it might 

 be one with E. argenteus, Mich. (=£. parvulus, Friend). 

 Bretscher examined the subject again in 1902, and decided 

 that the two were distinct. The author, who had alreadv 

 described E. argenteus, has found E. minimus at Buxton, 

 and holds with Bretsche. Fridericia peruviana, n.sp., was 

 received in earth from Peru, and submitted to the author 

 by the authorities at Kew. It is 5-6 mm. in length, and 

 has two to five setae, which are somewhat larger behind 

 than before. Brain slightly concave posteriorly ; oesophagus 

 sharply marked of! from intestine; dorsal vessel post- 

 clitellian m origin, with dilatations in segs. 7-9. Salivary 

 glands not branched; long.— Walter Ba^shaw : Instant- 

 aneous exposure in photomicrography. Flashlight illumina- 

 tion has been put to a novel use by Mr. Bagshaw for the 

 photography through the microscope of objects in motion. 

 A good negative of fresh-water polvzoa (Lophopus crystal- 

 Itnus) expanding its tentacles was secured by a charge of 



-Agfa Flashlight Powder" in one-thirtieth of a second, 

 leatherings of pond life, such as diatoms, larvje, water 

 fleas, also yielded successful results. Provision was made 

 tor replacing the ordinary lamp bv flash powder put in the 

 position previously occupied by the centre of flame, and 

 ignitjon' made with a red-hot wire. 



Manchester. 

 Literary and Philosophical Society, October 17 — 

 Prof. F. E. Weiss, president, in the chair.— H. J. 

 Woodall : Mersenne's numbers. In 1644 Mersenne pub- 

 lished a book entitled " Cogitata Physico-Mathematica." 

 in which It was stated that certain numbers obtained bv 



NO. 2192, VOL. 88] 



raising 2 to the power p, where ^ is a prime number not 

 greater than 257, and subtracting unity from the result, 

 would be factorisable except in twelve specified instate 

 He left no clue as to how he arrived at this result, 

 is any method known by which he could have <! 

 Subsequent eximination has shown that the stai 

 incorrect in two cases, one case being prime where .. 

 composite, and the other the reverse, but most of tl 

 which, according to him, are factorisable, have l< 

 proved to be so. Mr. Woodall gave a proof that il»c 

 number obtained by subtracting unity from the iSist 

 power of 2 is divisible by 43,441, the quotient contaii/ 

 fifty figures. He explained the method by which 

 divisor had been arrived at, and stated that the number i>i 

 unproved cases is now reduced to sixteen (fifteen composites 

 and one prime) out of a total of fifty-six. — S. Hiret : A 

 collection of Arachnida and Chilopoda made by Mr. S 

 Neave in Rhodesia north of the Zambezi. The paper d 

 with the scorpions, Pedipalpi, Solifugae, and centip' 

 collected by Mr. Neave. Four new species are descrii 

 two of which were obtained by Mr. Neave, the remaining 

 two being specimens in the British Museum, that were 

 obtained from the same area. The new species present no 

 features of special interest, differing only in certain details 

 of the appendages from already known forms. Two of the 

 species obtained by Mr. Neave had only been captured once 

 previously, and are thus of interest from this point of 

 view. 



Paris. 

 Academy of Sciences, October 16. — M. Armand Gamier in 

 the chair. — Ch. Bouchard : The velocity of parachutes. 

 A certain time after starting a parachute the velocity be- 

 comes uniform, and this velocity depends on the ratio of 

 P, the weight, and S, the horizontal projection, of the 

 carrying surface. The application of the ordinary re- 

 ance formula for air, in which the resistance depend- 

 the square of the velocity, to these measurements, j, 

 unsatisfactory results, but a formula involving the sq; 

 rot)i of tlie cubf of the velocity (\") was found to n. 

 well with the experiments. — M. Borreliy : Observatior 

 the Bcljawsky comet (1911^) made with the comet fii 

 at the Observatory of Marseilles. The positions are g; 

 for October i and 2. On October i the comet was \ 

 bright, and visible to the naked eye. The tail was \\!1 

 marked, and extended about 15° from the nucleus. On the 

 following day the appearance of the comet had compi' 

 changed, the nucleus being surrounded by a circular ! 

 two aigrettes showing on the right and left. — M. Nicolau . 

 The variation in the movement of the moon. — A, 

 Demoulin : The R and -■ surfavt-s. — Etiennc Delassus : 

 The non-linear linkages and the movements studied by 

 M. Appell. — Marcel Brillouin : An interferential method 

 for the determination of the moduli of torsion of cryst.ils. 

 The deformation of the surface of a crystal plate under 

 flexion can be studied by means of the interference frin;:' 

 the measurements being made with a metallogr.i; 

 microscope under a low magnifying power. It is sh 

 that all the moduli can be calculated from such mea'- 

 ments. — Georges Claude : The volatilisation of the • 

 trodes in neon tubes. It has been shown in a previous 

 note that tho gases obtained by the treatment with nitric 

 acid of the film of volatilised metal contain, besides neon, 

 a considerable proportion of helium. Three hypotheses may 

 be put forward to account for this fact : the pos'^''^''^ 

 selective action of the volatilised metal on helium • 

 tained in the neon in a proportion too small to be det» 

 by the spectroscope, the transformation of neon 

 helium, or the possible transformation of a portion of 

 neon into compounds retained by the nitric acid. 1 lie 

 experiments described in the present paper support the 

 first of these hypotheses, the selective action of the metal, 

 and this conclusion is in accord with the results of Ramsay 

 and Collie arrived at in a different way. — A. Rosenstiehl : 

 The theory of complementary colours. — P. Janet* 

 F. Laporte, and R. Jouaust : The determination of the 

 electromotive force in absolute measure of the normal 

 Weston element. In an earlier publication the electro- 

 motive force of the Weston cell had been found by the 

 authors to be 101869, '" terms of the true ampere and 

 the international ohm. Comparison of the ohm used with 

 those of foreign laboratories reduces this figure to i 01859, 



