162 



NA TURE 



[ June 12, 1 1 



Roy. Six:., vol. xxxii. p. 454), when I found that the flame hail 

 penetrated into every working place in the mine. The plan 

 which accompanies No. III. paper shows that all the working 

 places were ventilated by what was, practically, a single current 

 of air. It was, therefore, open to those who attribute every 

 great explosion to the occurrence of a sudden outburst of fire- 

 damp, and, as the annals of mining show, they constituted a 

 very large majority before the appearance of my first paper on 

 coal-dust, to say that this explosion was due to the same cause. 

 For this reason I have paid particular attention to the pheno- 

 mena due to the explosion which occurred at Dinas Colliery on 

 January 13, 1879. I do not propose to enter into the minute- 

 details of this case, as I should to a large extent simply be 

 repeating what I stated about Penygraig explosion, but will con- 

 fine myself to those which are necessary or new. I had fre- 

 quently inspected the workings before the explosion, and I have 

 done so at intervals of one month or less since then, so that I 

 have been intimately acquainted with all the conditions of the 

 mine for many years. I know also that no sudden outburst of 

 fire-damp has ever been known to take place in it. The workings 

 were naturally very dry, the temperature ranging from 75° to 82° 

 F., and the floor was covered with coal-dust. Shot firing was 

 carried on by night when the explosion happened. The damage 

 done by the explosion was very great, the workings being 

 wrecked to such an extent as to lead to their temporary 

 abandonment. They were reopened after a large expenditure 

 of time and labour, and it was only towards the end of last 

 year that I was able to inspect one of the districts of working 

 places, and early in the present year that I could get into the 

 other. With the exception of some burnt hay or dried grass 

 which I found in one of the return air-ways, I saw no traces of 

 burning nor deposits of coked coal-dust in any of the main road- 

 ways, but I found well-marked deposits of coked coal dust in 

 all the working places in both districts of workings as far as I 

 was able to penetrate. The plan shows that the current of fresh 

 air which came down the downcast shaft was split up into three 

 separate currents. The two districts were thus ventilated quite 

 independently of each other, and it was therefore impossible 

 for any outburst of fire-damp which might take place in one of 

 them to affect the quality of the air in the other. 



We are thus compelled to fall back upon some other mode of 

 explanation in this case, and I now submit that in the present, 

 and in my previous papers, I have brought forward sufficient 

 evidence to show that the coal-dust hypothesis is the only tenable 

 one. If it be admitted, however, that this hypothesis is ap- 

 plicable to Dinas explosion, the conclusion is inevitable that, 

 cateris paribus, it is equally applicable to every case of the same 

 kind that has ever occurred. 



Zoological Society, June 3. — Prof. A. Newton, F.R.S., 

 vice-president, in the chair. — A letter was read from Mr. Albert 

 A. C. Le Souef, C.M.Z.S., of the Zoological Gardens, Mel- 

 bourne, giving an account of the unusual occurrence of two young 

 ones being produced from one egg laid by a black-necked swan. 

 The writer described the appearance of these cygnets, which 

 were much smaller than a companion bird of the same age. — 

 Mr. F. E. Beddard read a paper upon the visceral anatomy of 

 Hapalemur griseus, and called attention to the various points of 

 difference between this species and Hapalemur simus. — Mr. A. 

 D. Bartlett read a paper on some singular hybrids of bovine 

 animals bred in the Society's Gardens. — Mr. G. E. Dobson, 

 F.R.S., read a paper on the unimportance of the presence or 

 absence of the hallux as a generic character in Mammalia, as 

 evidenced by the gradual disappearance of this digit within the 

 limits of a single genus [JErinaceus). — A communication was read 

 from Mr. II. W. Bates, containing a list of the Coleoptera of the 

 families Carabidte and Scaralxeidte collected by the late Mr. W. 

 A. Forbes on the Lower Niger. Of these three appeared to be 

 previously undescribed. — Dr. Carl Lirmholtz read a paper con- 

 taining notes upon some mammals which he had recently dis- 

 covered in Queensland. 



Anthropological Institute, May 13. — Prof. Flower, F.R.S., 

 president, in the chair. — Dr. Maxwell T. Masters exhibited a 

 series of agricultural implements brought by Mr. Livesay from 

 the Naga Hills, at the north-east corner of Assam. The tools 

 were chiefly such as are used for rice culture on the irrigated 

 slopes of the hills, and consisted of rakes made of bamboo and 

 wood, a hoe and iron knife with wooden sheath and cord for 

 suspension. — Dr. J. Stephens sent a drawing of a large pointed 

 palaeolithic implement recently found near Reading, length 9] 

 inches, weight 2 lbs. 3i oz. — Mr. W. G. Smith exhibited two 



palaeolithic implements recently found in North London. One 

 was made of quartzite, and is the first example of this material 

 met with in the London gravels ; the other was a white imple- 

 ment from the " trail and warp." He also exhibited two white 

 porcellaneous palaeolithic flakes replaceel on to their original 

 blocks ; the four pieces were found by him in North London, 

 wide distances apart, at different times during the last six years. 

 — Mr. Smith also exhibited a large axe from New Guinea with a 

 keen blade of siliceous schist or banded chert, 94 inches long, 

 and weighing over 2^ lbs. The axe was sent home by a sailor, 

 and Mr. Smith purchased it of a person who was using it in North 

 London for chopping up firewood. — A paper on the ethnology 

 of the Andaman Islands, by Mr. E. II. Man was read. — Prof. 

 Flower read some additional observations on the osteology of the 

 natives of the Andaman Islands. Since reading a paper before 

 the Institute on the same subject in 1879, the author had had the 

 opportunity of examining ten additional skeletons, two of which 

 are in the Museum of the University of Oxford, and eight in the 

 Barnard Davis Collection now in the Museum of the Royal Col- 

 lege of Surgeons. Five are males and five females, and all are 

 adult. The measurements of these specimens have thoroughly 

 established the fact that the twelve skulls of each sex previously 

 examined furnished a very fair average of the characters of the 

 raee- 



Cambridge 

 Philosophical Society, April 28. — Mr. Glaisher, ; 

 in the chair. — The following communications were made to the 

 Society : — By Mr. R. T. Glazebrook, on the electro-magnetic 

 theory of light. — By Mr. A. H. Leahy, on the pulsation of 

 spheres in an elastic medium. The problem of two pulsating 

 spheres in an incompressible fluid has been discussed by several 

 writers. The author considers the analogous problem in the 

 case in which the medium surrounding the spheres has the 

 properties of an elastic solid. He finds that the most important 

 term in the expression of the law of force between the two spheres 

 varies inversely as the square of the distance between them. 

 This force will be an attraction if the spheres be in unlike phases, 

 a repulsion if they be in like phases at any instant. The next 

 term in the expression varies inversely as the cube of the distance 

 between the two spheres, and is always a repulsion. 



Edinburgh 



Royal Society, June 2. — Sheriff Forbes Irvine in the chair. 

 — Prof. Fait communicated a paper by the Rev. T. 1'. Kirkman 

 on the enumeration, description, and construction of knots. The 

 paper described the application of a particular set of the polyhedra 

 investigated by the author to the investigation of the subject. — 

 Prof. Tait then read the second part of a former paper of his 

 own on knots. He first considered the modification required to 

 lie made on Mr. [Cirkman's diagrams so that they might repre- 

 sent actual knots. He also took up the question of the identity 

 of some of the figures with the view of determining the actual 

 number of different knots having a given number of crossings. 

 Finally he recurred to the problem of beknottedness, showing 

 how it was to be determined in any case upon the consideration 

 thai locking may occur with two strings, and even with one, as 

 well as with three. — Mr. John Aitken read a second note on the 

 recent sunsets, showing how all the phenomena observed received 

 a satisfactory explanation on the hypothesis that they resulted 

 from the presence of abnormal quantities of dust particles in the 

 air. He pointed out that the facts considered adverse to iliis 

 conclusion really furnished additional proof. — Mr. Aitkin then 

 read a paper on thermometer screens, which gave rise to an 

 animateel discussion. 



Dublin 



Royal Society, May 19. — Section of Physical and Ex- 

 perimental Science. — G. F. Fitzgerald, F.R.S., in the chair. — 

 1 in the pitch-curves of cogged wheels, by A. II. Curtis, LL.D. 

 The author showed that a pitch-curve A, 0/ any form, its axis a, 

 and also the axis b of the corresponding pitch- curve B, being 

 given, the curve B must be such that, if it roll without sliding on 

 A (the initial point of contact c being of points which in work- 

 ing would come together), carrying l> with it, the roulette thus 

 described by b will be a circle having a for centre ; hence he 

 deduced the known result that the point of contact of the pitch- 

 curves must be situated on a b — for the tangent at b to the rou- 

 lette must be perpendicular to b c, while, as this roulette is a 

 circle, this tangent must also be perpendicular to a b ; he proved 

 that, if / = $ (r) be the equation of A, p' = -, <J> (f - r'), 



