July 27, 1905] 



NA TURE 



301 



The light given out by the platino-cyanides is, as a rule, 

 vivid and partially polarised ; it disappears directly the 

 exciting cause is withdrawn. Crystals of scheelite, 

 phosgenite, &c., show a feeble luminescence lasting several 

 seconds after the removal of the incident rays. 



In part i. of a contribution to the Scientific Transactions 

 of the Royal Dublin Society, vol. viii., p. ib, Prof. A. W. 

 Conway discusses the partial differential ecjuations of 

 mathematical physics which in their general form are 

 partial differential equations of the second oi-der with 

 constant coefficients reducible by transformation to three 

 different classes. The problem has been attacked by 

 Whittaker from the point of view of building up singular 

 solutions from plane-wave solutions, but Prof. Conway 

 adopts the reverse course, starting with the singular 

 solution. 



Among the results of the recent Rontgen congress at 

 Berlin has been the authoritative adoption by a special 

 committee of the following terminology : — Rontgenology = 

 the study of Rontgen rays, Rontgenoscopy = observation 

 by Rontgen rays, Rontgenography = photography by the 

 rays, Orthorontgenography in place of orthodiagraphy, 

 Rontgenotherapy and the verb to rontgenisc in their obvious 

 meanings. 



The question "What is research?" is discussed by 

 Prof. Henry S. Williams in the Popular Science Monthly. 

 The author considers that research is not a special faculty 

 possessed by the few, but a common faculty specially 

 trained and systematically exercised by the few, for whom 

 it becomes a tool of the highest value, and the means of 

 opening up new fields of knowledge to mankind. At the 

 same time, he directs attention to the detrimental effects 

 of too much book learning on the power of research, and 

 the need of a vivid imagination such as can be exercised 

 and disciplined by the study of mathematics. Moreover, 

 the man of research must be prepared to sacrifice his 

 prospects in other directions and to work alone, " un- 

 appreciated and unapplauded " in most of his work, and 

 Prof. Williams finally cautions teachers against tempting 

 mere enthusiasts to undertake a task which requires for 

 success the toughness of a soldier, the temper of a saint, 

 and the training of a scholar. The subject of the article 

 is one which might be very well discussed further in view 

 of the large amount of " research," falsely so-called, which 

 is now being turned out by persons not possessing any of 

 these qualities, with the great danger of lowering public 

 estimation of the importance of work of real scientific 

 value. 



Dr. J. Hettinger, writing from London in the 

 Physikalische Zeitschrift for June 15, describes a new 

 electrical connection for intensifying the resonance effects 

 in wireless telegraphy. 



The Mathematical Association has reprinted the report 

 of its committee on the teaching of elementary mathe- 

 matics. In the same pamphlet are reproduced the " Little 

 Go " regulations in geometry. We observe that Cam- 

 bridge advocates the " hard pencil," which leads to so 

 many indistinct figures in candidates' answers. A valuable 

 mental training is thus omitted in not requiring candidates 

 to make their drawings, as well as written work, clear 

 and distinct to others. Moreover, even a soft pencil with 

 a thick point has an advantage in showing that in any 

 constructive proof lines must necessarily be of a certain 

 thickness, and the conclusion is only established as approxi- 

 NO. 1865, VOL 72] 



matelv true. The beginner who learns this will be the 

 better able to appreciate the deductive method at the 

 proper time. 



The surfaces obtainable by the deformation of a hyper- 

 boloid of revolution of one sheet are discussed by Prof. 

 Luigi Bianchi in the Atti of the Lincei Academy, xiv., 10. 

 The determination of these surfaces is shown to depend on 

 that of a certain class of imaginary pseudospherical 

 surfaces, and the difficulty of the problem is reduced to 

 that of characterising these latter surfaces, and thus pre- 

 senting the final transformation formulas in a real and 

 definite form. 



The Institution of Electrical Engineers has published an 

 address delivered to its students in January last by Mr. 

 James Swinburne, M.Inst.C.E., on " The Theory of 

 Electricity and the Value of its Study to Engineers." In 

 it the author emphasises the desirability in many cases of 

 mathematics being learnt through its applications, and 

 points to the theory of electricity as affording a valuable 

 introduction to the study of many of the most important 

 branches of mathematical analysis. In conclusion the 

 author says : — " I feel confident that enough has been said 

 to make it evident that a modern engineer cannot consider 

 his technical equipment complete without some knowledge 

 of the theory of electricity; and if electrical development 

 continues at the present rate it may soon be the most 

 important branch of the science of engineering." 



Biologisches Centralblatt of July i contains the report 

 of an interesting address on the use and place of hypotheses, 

 suppositions, and problems in biology, delivered by Mr. 

 J. Reinke at the opening session of the International 

 Botanical Congress at Vienna on June 12. That theories 

 and hypotheses have a great and important place in science 

 — indeed, that they are absolutely essential to its proper 

 advance — the lecturer fully admitted ; but, he added, it 

 is necessary to remember that they are nothing more than 

 theories, otherwise there is the greatest danger of their 

 proving a hindrance and an illusion. A notable instance 

 of this danger is afforded by the numerous phylogenies of 

 animals and plants which are published from time to 

 time, and are too often accepted as though they were 

 solid facts, instead of being in most cases mere hypotheses, 

 based not unfrequently on the very slenderest of founda- 

 tions. 



.A YEAR ago we referred to notices of the occurrence of 

 the striped hawk-moth in this country, and we observe 

 that in the Entomologist for June and July several in- 

 stances of the capture of the same species this season are 

 mentioned. Possibly this handsome moth may become 

 established in the south of England, at least for a time. 

 In the July number Mr. G. W. Kirkaldy continues his 

 popular synopsis of British water-bugs. 



To the Journal of Conchology for July Mr. A. D. 

 Darbishire contributes a discussion on Prof. Lang's ex- 

 periments in breeding with the two common garden 

 snails Helix hortensis^ and H. nemoralis. The writer 

 denies that these experiments confirm the truth of Mendel's 

 doctrine, stricto sensu ; that is to say, they do not afford 

 conclusive evidence of the existence in the gonads of H. 

 hortensis of definite unit-bearing elements representing 

 either five-banded or unhanded shells. It is added that 

 much interest will attach to the description of the char- 

 acters of the " dart " in the hybrid between the two species 

 in question. 



