Nov. 7, 1889] 



NATURE 



1 1 



correct, the leaves of the electroscope in connection with this 

 plate should show an increa'-ed divergence, but the reverse effect 

 was observed. The leaves partially c-dlapsed. In all experi- 

 menls that I have made by inserting dielectrics between a charged 

 body and an electroscope, less electric action has been the result. 

 If while the charged ball be near the electroscope the plate of 

 it be touched with the finger, the leaves collapse, and on removing 

 the finger and then the charged ball they again diverge. 



Now let a dielectric be placed between the ball and the 

 electroscope, touch the latter, and remove the finger and ball as 

 before, and much greater divergence will be produced. In both 

 cases the electroscope is charged by induction. Without putting 

 the electroscope to earth, 1 fail to see theoretically why any 

 greater divergence should occur. I suppose someone must have 

 made the experiment as quoted, but if a greater effect was 

 produced it must have been caused by the substance used for a 

 dielectric being charged itself I have found very great difficulty 

 in preventing plates of ebonite, paraffin, sulphur, &c., becoming 

 electrified when placed near a charged body. 



I should like to know if anyone has experimented in this 

 direction, because either the text-books or myself must be wrong. 



In Guthrie's book (p. lOi) there is a statement similar to 

 Ganot's. W. A. Rudge. 



Who discovered the Teeth in Ornithorhynchus .' 



On returning from Central Arizona, where I have been engaged 

 in biological explorations, I find upon my desk an important 

 paper entitled " On the Dentition of Ornithorhynchus," by my 

 friend Mr. Oldfield Thomas, Curator of Mammals in the 

 British Museum (see Proc. Royal Soc, vol. xlvi , 1889, 126-131, 

 pi. 2). 



The opening sentence of this paper is as follows : "At the 

 meeting of the 9th of February, 1888, Mr. E. B. Poulton com- 

 municated to this Society the first discovery of the presence of 

 teeth in Omitho>Jiynchus, a discovery which naturally awakened 

 extreme interest throughout the scientific world." A few lines 

 further on Mr. Thomas continues : " The grand fact of the pre- 

 sence of teeth in Monotremes, and their mammalian nature, are 

 discoveries on which Mr. Poulton may well be congratulated." 



From the above I infer that consideiable stir has been made 

 by the assumed new ' ' discovery " that the young Ornithorhynchus 

 has teeth. 



If my British colleagues will turn to the masterly work of 

 their illustrious countryman. Sir Everard Home, they will find 

 in the second volume of his "lectures on Comparative 

 Anatomy" (published in 1814), no less than three beautifully 

 engraved plates, containing eight figures, of the skull and mouth 

 parts of Ornithorhynchus. Four of these figures show the teeth 

 — two on each side of each jaw. The explanation accompany- 

 ing Fig. I, Tab. lix., is as follows: "A view of the upper jaw and 

 palate, to show that there are two grinding teeth on each side." 

 ¥\g. 2 is "a similar view of the under jaw." 



Washington, D.C., October 12. C. Hart Merriam. 



ON THE HARDENING AND TEMPERING OF 

 STEEL} 



I. 



THE fact that the British Association meets this year 

 at Newcastle no doubt suggested to the Council 

 that it would be well to provide, for the first time since 

 1848, a lecture on a metallurgical subject. In that year 

 a discourse was delivered at Swansea by Dr. Percy, one 

 of the most learned metallurgists of our time, who has 

 recently passed away, after having almost created an 

 English literature of metallurgy by the publication of his 

 well-known treatises, without which it would have been 

 comparatively barren. It was to him that the country 

 turned in 1851 when it became evident that our metal- 

 lurgists must receive scientific training. 



1 know that it has occurred to many that the various 

 problems involved in the " hardening and tempering of 

 steel " must be incapable of adequate treatment in the 

 brief limits of a discourse like this, while others will think 



' A Lecture delivered on" September 13, by Prof. W. C. Roberts-.\usten, 

 F.R.S., before the members of the British Association. 



that the details of the process, which is practised daily in 

 thousands of workshops, are so well known that it is un- 

 necessary to devote a lecture to the subject. It seemed 

 to me that the entire question was the most important I 

 could choose, partly because it will enable a large number 

 of people who are engaged in industrial work, and who 

 are not expected to think about it in a scientific way, to 

 know how such facts as we shall have to examine have 

 been dealt with by scientific investigators ; while those of 

 our members who do not consider that their thoughts or 

 work are scientific in its strictest sense, may perhaps be 

 interested to see how absolutely industrial progress de- 

 pends upon the advancement of science. This consider- 

 ation has led me to deal with the subject in a somewhat 

 comprehensive way. The treatment of iron in its several 

 forms is the thing that we as a nation do well. If it be 

 true that national virtues are manifestly expressed in the 

 industrial art of a people, we may recall the sentence in 

 Mr. Ruskin's " Crown of Wild Olive" in which he says, 

 " You have at present in England only one art of any con- 

 sequence—that is, iron-working," adding, with reference 

 to the manufacture of armour-plate, " Do you think, on 

 those iron plates your courage and endurance are not 

 written for ever, not merely with an iron pen, but on iron 

 parchment ? " It may be well, therefore, to consider what 

 properties iron possesses which entitle its application to 

 industrial use to specially represent the skill and patience 

 of the nation. 



In 1863, Lord Armstrong, in his address as President 

 of this Association, expressed the hope " that when the 

 time again comes round to receive the British Association 

 in this town, its members will find the interval to have 

 been as fruitful as the corresponding period," since the 

 previous meeting in 1838, "on which they were then 

 looking back." In one way at least this hope has been 

 realized, for the efforts of the last twenty years have re- 

 sulted in the development of an " age of steel." When 

 the Association last met here, steel was still an expensive 

 material, although Bessemer had, seven years before, 

 communicated his great invention to the world through 

 the British Association at its Cheltenham meeting. The 

 great future in store for Siemens's regenerative furnace, 

 which plays so important a part in the manufacture of 

 steel, was confidently predicted in his Presidential address 

 by Lord Armstrong, than whom no one was better able to 

 judge, for no one had done more to develop the use ot 

 steel of all kinds. 



Steel, we shall see, is modified iron. The name iron is 

 in fact a comprehensive one, for the mechanical behaviour 

 of the metal is so singularly changed by influences acting 

 from within and without its mass, as to lead many to 

 think, with Paracelsus, that iron and steel must be two 

 distinct metals, their properties being so different. Pure 

 iron maybe prepared in a form as pliable and soft as copper, 

 steel can readily be made sufficiently hard to cut glass, 

 and notwithstanding this extraordinary variance in the 

 physical properties of iron and certain kinds of steel, the 

 chemical difference between them is comparatively very 

 small, and would hardly secure attention if it were not for 

 the importance of the results to which it gives rise. We 

 have to consider the nature of the transformations which 

 iron can sustain, and to see how it differs from steel, of 

 which an old writer has said,i " Its most useful and ad- 

 vantageous property is that of becoming extremely hard 

 when ignited and plunged into cold water, the hardness 

 produced being greater in proportion as the steel is hotter 

 and the water colder. The colours which appear on the 

 surface of steel slowly heated direct the artist m teinper- 

 ing or reducing the hardness of steel to any determmate 

 standard." There is still so much confusion between the 

 words " temper," "tempering," and " hardening," m the 

 writings of even very eminent authorities, that it is well 



' " The First PrincipIeE of Chemistry," ly V . Nicholson, p. 3'2 (London, 

 1790). 



