2 S6 



SCIENTIFIC NEWS. 



[Sept. 14, if 



there were absolutely no rules for the guidance of people who de- 

 sired to erect lightning-conductors for the protection of their houses. 

 In that year a great conference was held on the subject, and the re- 

 sult of its deliberations was published in a book, and included a set 

 of rules for the construction of conductors. He had under his per- 

 sonal observation no less than 500,000 lightning-conductors. Some 

 time ago a lectureship was founded in memory of Dr. Mann, who 

 had experimented on the projection of buildings from lightning in 

 South Africa. Professor Oliver Lodge was selected as the 

 lecturer, but instead of cracking up the work of the Conference, he 

 took the other line, and if his statements were true, lightning-con- 

 ductors would be of no use, and no buildiDgs would be sale in a 

 thunderstorm. Professor Oliver Lodge had committed himself to 

 fallacies which it was now his (the speaker's) duty to bring before 

 the meeting. The professor assumed that a lightning-rod formed 

 part of the flash. Well, as a matter of fact, it did not. Nobody 

 had ever seen a flash of lightning strike a conductor. The function 

 of the conductor was to prevent the possibility of the building on 

 which it was erected being struck by the flash of electricity. 

 If a building was struck there was some defect in the 

 construction of the conductor. Lightning did not go careering 

 wildly about, but passed along a path prepared for it. There was 

 another fallacy which prevailed, and that was that a flash of light- 

 ning was instantaneous. No proof, so far, had been produced of 

 that. They saw a flash of light which indicated part of the dis- 

 charge, but how long that discharge lasted they did not know. 

 There were invisible flashes of lightning, which was proved by the 

 fact that persons had been killed under trees when there was no 

 visible flash. He had, however, come to the conclusion, by the 

 (fleet on telegraph wires, when there were currents of sensible 

 duration, that the flash was not instantaneous. He argued 

 that if Professor Lodge were correct no lightning-conductor could 

 protect, and no discharge could possibly be led to the earth. The 

 assertion of the oscillatory character of the lightning flash was based 

 more on mathematical reasoning than it was upon absolute observa- 

 tion. There were those amongst mathematicians who made 

 mathematics their slaves, and when they got into the slough of 

 despond they found it difficult to get out again. Engineers had no 

 great respect for mere mathematical development, unless it was proved 

 by absolute experiment. Mathematical developments should be re- 

 ceived with extreme caution, and the theory, beautiful as it was, must, 

 as he had before remarked, be received with great circumspection. 

 There were several facts against the proposition. As to the theory of 

 self-induction there was also much doubt. There was no doubt that 

 Professor Lodge had started a new and fresh hare which electricians 

 must hunt up and kill. Professor Lodge was on the brink of a great 

 discovery, although he (the speaker) did not accept his theory of 

 self-induction. Whatever the result of the present conference was, 

 he would certainly have the advantage of bringing to the front what 

 they were all anxious to see — namely, the true theory of electricity 

 shadowed forth by Professor FitzGerald in his address, which would 

 mark the present meeting of the Association as an important epoch 

 upon that subject. 



Professor Oliver Lodge, F. R.S., said he had had nothing like 

 the experience of Mr. Preece. So far from having half a million 

 lightning-conductors under his supervision, he had not got a solitary 

 one. He had frequently asked his friends to put up conductors on 

 their houses, but the answer he invariably received was that 

 conductors were too expensive, and "it was cheaper to insure." It 

 was perfectly true, as Professor Preece had said, that few public 

 buildings were effectively protected from l r ghtning, the reason being 

 that the conductors used were not efficient. If conductors were 

 used on all lofty buildings, their price would probably be as many 

 shillings as they now cost pounds to put up, and the result would be 

 a great saving to life and property. Mr. Preece had said that a 

 properly constructed conductor had never failed to do its work, but 

 he (the speaker) could not quite agree with that statement, for he 

 thought that lightning-conducors had frequently failed to act w r hen 

 they were called upon to do so. The Hotel de Ville at Brussels 

 was supposed to be protected from lightning by innumerable con- 

 ductors, but nevertheless on the 1st of June last year it was struck 

 by the electric fluid and set on fire. The lightning-rod had two 

 functions— one was to act as a point to attract the flash, and the 

 other was to carry cfl the fluid. It was not desirable that con- 

 ductors should immediately take the fluid to the earth, for it was 

 often belter to allow the great energy of the flash to slowly exhaust 

 itself. He thought the address they had listened to was a very 

 interesting one, and he considered that the thanks of the section 

 ought to be accorded to Mr. Preece for his lecture. 



The Hon. R. Abercromby, who followed, produced a number of 

 photographs of lightning flashes. He felt sure good would result 

 from the discussion. 



Lord Rayleigh observed that whatever might be the failings of 

 mathematicians, he felt that scientists must go to them eventually. 



Sir William Thomson, F.R.S., could not help thinking it 

 would be well for the Professor to continue his experiments in regard 

 to the superiority of iron over copper rods. As to protecting buildings, 

 he must confess that it was rather disturbing to find that lightniog- 

 rods hsd so little protecting power. Before, however, iron was 

 generally recommended for lightning-rods, further experiments must 

 be carried out with regard to the conducting power of that metal. 



Professors Forbes and Rowland (of John's Hopkins College, 

 U.S.A.) and M. de F. Fonvielle (of Paris) continued the discus- 

 sion, which, after a few observations from Mr. Sydney Walker, 

 Mr. Brown, and Mr. Wood, followed. 



Dr. J. Janssen, a foreign member of the Royal Society, read a 

 paper on Analyse Chrcnometrique des Phenomenes Electriques 

 Lttmineux, and Mr. R. T. Glazebrook, F.R.S., di'cussed the 

 Standard of Electrical Re istance. 



CHEMICAL SECTION. 



{Continued from p. 2 57.) 



Saturday, September 8th. 



Professor Tilden, F.R.S., presiding. 



The first business was to receive the report drawn up by Professor 

 Dunstan of the committee appointed for the purpose of inquiring 

 into and reporting on The Present Methods of Teaching Chemistry. 

 This was a very long and important report, which we shall pro- 

 bably give in cxtenso in a future issue. 



Trie President said he should like to offer a single criticism 

 on the foregoing report. If, as appeared to be admitted by every- 

 body, chemistry was such a valuable element in school education, 

 surely those advantages should be shared by girls. It was a very 

 extraordinary circumstance, but he did not notice a single reply from 

 a girls' school embodied in the report. It was a regrettable fact 

 that chemistry did not at present seem to have found its way into 

 girls' schools, and he could net help hut regard it as a serious 

 misfortune in the interests cf the higher education of women. The 

 report, in brief, confirmed the view expressed in his address, that 

 until they had teachers better qualified to impart instruction, these 

 difficulties would not be overcome practically. 



The Rev. A. Irving, in a paper on Chemistry as a School Subject, 

 said that chemistry could not properly be taught apart from physics ; 

 there was a physical side to every phenomenon. Lecture work 

 should precede laboratory work, and continue pari passu with it. 

 Analysis rationally, not mechanically taught, was an excellent 

 mental training. The two should be closely correlated ; exercises 

 should be given in the laboratory, preparatory to or suggested by 

 the subjects treated in the lectures, and facts learnt in the laboratory 

 should be turned to account in the lectures. The teacher must not 

 be trammelled by text-books ; these must be his instruments, not 

 his masters. Quantitative treatment of subjects in the lectures 

 should be introduced as far as possible from the first, and as pupils 

 advanced they should be trained individually in the use of the 

 balance. Numerical exercises based on (not as a substitu'e for) 

 lecture demonstration helped to give fixity and precision to ideas. 

 Pupils should be trained to think out, in their note-books, the 

 connecticn between experimental demonstration and theory, and 

 not have notes dictated to them to be committed to memory. 

 Their knowledge should also be tested by frequent short exmination 

 papers. 



Mr. Angel (Manchester), in opening the discussion, strongly 

 criticised the system of teaching boys chemistry by mere lectures 

 and note-taking. Such a method, he declared, involved utterly in- 

 compatible processes being set up in the ju\enile mind. It 

 engendered no scientific thought, and left no clear impression of any 

 phenomena on the mind. The result was entire failure. In nine 

 cases out of ten such a method of teaching made clear scientific 

 thought an impossibility. With regard to examinations, he held 

 that the present progress of science was more due to our system of 

 examination than anything else. 



Mr. Gatehouse (Bath) thought the report of the Committee in 

 some of its phases confounded the making of the intelligent man 

 with the making of the chemist. 



Miss Lydia Becker thought the Committee would do well to 

 entirely eliminate from their report the word boy, and substitute for 

 it pupil, student, or child. There were very many difficulties in the 

 way of girls sharing in the benefits to be derived from the study of 

 chemistry and physical science ; and there could be no doubt that it 

 was owing to such causes as these that the higher education of 

 women had not made more rapid progress. As regarded the mode 

 of teaching, she thought the habit of questioning pupils wis one 



