March 5, 1885; 



NATURE 



4i3 



cannot always contain questions that would be most suit- 

 able for one particular mode of teaching. The kind of 

 questions set would be of a different nature if the giving 

 of the questions devolved upon those who had in hand 

 the teaching. Those who have the teaching can give an 

 examination vastly more useful and one that would re-act 

 on the teaching in a way that an examination of a multi- 

 tude of students trained at all kinds of institutions, and 

 many merely by private reading, could not possibly do. 

 Therefore, it seems to be a matter of high importance 

 indeed that there should be a University of Wales ; that 

 you should consider it to be a great object to be attained, 

 sooner or later — but the sooner the better — the establish- 

 ment of the University of Wales, with the University Col- 

 lege of North Wales an integral part of it. I have much 

 pleasure in wishing the University College of North Wales 

 every success, and 1 trust that the laboratories now opened 

 may prove of great value in promoting and aiding the 

 study of science. 



POLYNOMIALS IN ZOOLOGY 1 

 O INCE the days of Linnaeus scientific zoologists have 

 v -' universally adopted the binomial system of nomen- 

 clature, which was invented and introduced by that great 

 naturalist. So long as the idea of the fixity of species, as 

 originally created entities, prevailed, there was no excuse 

 for deviating from the Linnean plan. Such an idea as a 

 transitional series between two species, or the division of 

 a species into two or more local forms, was hardly under- 

 stood by the older authors. But of late years, since the 

 general acceptance of the derivative origin of species, it 

 has become universally acknowledged that sub-species 

 and transitional forms do exist in Nature, and many and 

 various plans have been proposed for indicating them. 

 Trinomials — that is, the usage of three names, of which 

 the last is that of the sub-species — are in great favour 

 with a rising section of American zoologists, and there 

 is much to be said in their defence. But the concession 

 of three terms, it is said, would in some cases not be suf- 

 ficient. Ouadrinomials and Polynomials must necessarily 

 follow, and render nomenclature inconveniently long. 

 Mr. S. Garman, the well-known herpetologist of the Com- 

 parative Museum of Zoology at Harvard College, Cam- 

 bridge, replies, in the pamphlet now before us, to the 

 assertion " that there is no other or better method than 

 " polynomials." Mr. Garman proposes to designate the 

 different forms or sub-species of a species by symbols 

 such as (A), (B), (C), (D). Supposing that the (C) form 

 is found to consist of several sub-varieties he would name 

 them (C. a ), (C. b ), (C. ). Still further subdivisions might 

 be indicated as forms (C al ), (C-), (C 3 ), and (C a "), (C* 1 "), 

 &c. Thus the polynomial " Amblystoma tigrinum mavor- 

 tium hallowelli suspeetum maculatissimutn " would be 

 reduced to " (C. a1 ') Amblystoma tigrinum" the " advan- 

 tage " of which for general literature is " apparent " ! But 

 is not this a case in which it may be said that the pro- 

 posed remedy is as bad as the disease ? 



TEMPERED GLASS 

 \A7'E are very pleased to be able to chronicle an appli- 

 * * cation which Mr. Frederick Siemens has recently 

 made in his regenerative gas radiating furnace, described 

 in the autumn of last year (Nature, vol. xxxi. p. 7). 

 It consists in the production of glass which appears to 

 be of a very homogeneous character and of considerable 

 strength and hardness, and will doubtless become avail- 

 able for a number of useful purposes. The scientific 

 principle which is applied in the three distinct processes 

 to which we propose to refer shortly, is that of keeping 



1 "On the Use of Polynomials and Names in Zoology." By S. Garman, 

 Cambridge, Mass., U.S.A. From the Proceedings of me Boston Society of 

 Natural History, March 10, 1884. 



the whole body of the glass at a uniform temperature 

 during the operations of heating and cooling — that is to 

 say, that at each unit of time the whole mass shall be at 

 one temperature. Two methods have hitherto been em- 

 ployed by means of which glass has been rendered more 

 or less independent of variation of temperature. The 

 oldest of these is that carried on in the annealing kiln, in 

 which the manufactured articles of glass are allowed to 

 cool very slowly. The more modern is that of De la 

 Bastie ; in this process the finished articles of glass had 

 generally to be annealed in the first instance, then heated 

 to such a temperature as to soften them, when they were 

 immersed in a bath of heated oil maintained at a tempera- 

 ture above 300° C, which was said to make them tough. 

 The objection to annealing is mainly that of cost, but the 

 objection to the De la Bastie process is that it is wrong 

 in principle, as, owing to the manner in which cooling is 

 effected, the glass is in a state of tension throughout, 

 which is brought to evidence by means of the polariscope. 

 The glass produced by the processes to be described are 

 almost free from internal strain, and Mr. Siemens holds 

 that, could the principle he propounds be carried out per- 

 fectly in practice, the glass would be free from tension 

 throughout its whole mass. A corollary which may ap- 

 parently be drawn from this proposition is that every 

 metal not cooled in the way proposed is in strain ; but 

 that, owing to the much greater tensile strength of metals, 

 the state of tension does not become evident in the same 

 manner as in glass, which is notably brittle. 



Press-hardened Glass. — Only glass of the very best 

 quality is suitable for hardening. It is cut into the pro- 

 posed shapes and placed in the radiation furnace until 

 soft ; it is then removed and placed between cold metal 

 plates, and cooled down in the proportion of its volume 

 or capacity for heat. Glass may be cooled so rapidly by 

 this means that the diamond will not touch it ; the pro- 

 cess is mostly applied to sheet and plate glass, which 

 may either be plain or decorated, and whose strength is 

 thereby increased eight times. The degree of hardening 

 which may be attained depends on the temperature to 

 which the glass is heated and the rate at which it is 

 cooled. The higher the temperature, and the more 

 quickly the glass is cooled, the harder is the glass. Thus, 

 for very quick cooling copper plates are used in the 

 presses, and the glass is rendered exceedingly hard ; 

 when a less degree of hardness is desired, iron plates, or 

 even these covered with asbestos, or clay slabs, may be 

 employed. 



Sheet-glass of ordinary thickness is heated in a minute 

 and cooled in half a minute. It is remarkable that this 

 can be effected in so short a space of time without injury 

 to the glass, and is due to the uniformity of the heating 

 and cooling operations. Owing to the high temperature 

 at which this process is carried on, more refractory 

 enamels, such as those used for porcelain, can be applied, 

 and the enamel is thus rendered as indestructible as the 

 glass itself. 



Semi-hardening is employed for goods to which presses 

 cannot be easily applied. The glass is heated up to a high 

 temperature, but not to such a degree as to affect its shape, 

 and is then placed within an iron casing having internal 

 projecting ribs so arranged as to hold the glass article in 

 position and to touch it at the fewest possible points. 

 The casing with its inclosure is cooled in the open air. 

 The process is only applicable to articles of nearly uni- 

 form thickness throughout ; it increases the strength of 

 the glass about three times, and renders it less liable to 

 be effected by changes of temperature than ordinary 

 glass is. 



The third kind of glass, which is known as hard-east 

 glass, has not yet been introduced commercially, but 

 samples of the work produced in the form of sleepers, 

 tramway-rails, grindstones, and floor-plates were exhibited 

 at the meeting. The method of production is very simple. 



