Feb. 1 8, 1886] 



NA TURE 



?8i 



was a brilliant success, and the experiences noted in this paper 

 are of great value ; but the result to the patient may be guessed 

 at by his exclamation some months after the operation : " C'etait 

 mieux quand je ne voyais pas." — On the action produced on the 

 sensibility and motility of nerves by dilute hydrochloric acid, 

 by Dr. C. Negro. — Note on pneumonococcus, a grave com- 

 plication in pneumonia, by P. Foa and G. Rattone. — On the 

 physio-pathological aspects of stratified pavement epithelium, 

 and on the pathogeny of albuminuria, by Prof. G. Tizzoni. — 

 On the presence of albumen in saliva, a criticism of the views of 

 Madame Dessales by Prof Brancaccio, and a reply by Madame 

 Dessales. — On the central termination of the optic nerve in 

 some mammals, by Dr. J- Bellonci. — On the influence of chloral 

 on gastric digestion, by A. Fiumi and A. Favrat. — Anatomical 

 and clinical study of Morgagni's cataract ; and on congenital 

 micro-ophthalmy, by Dr. Falchi. 



Rivista Scientifico-Indiistriale, December 15-31. — Dr. Pietro 

 Cardani, variation of the diameter of the sparks with the poten- 

 tial and the resistance : a study of the way the diameter of the 

 sparks is modified by the resistance of the circuit, and how the 

 diameter itself varies with the increase of the explosive distance. 

 The diameter is found to increase proportionately to the square 

 root of the potential, and to decrease according to a hyperbolical 

 function with the increased resistance ; hence for great distances 

 this diameter becomes sensibly constant. The same physicist 

 deals with Harris's second law that the explosive distance varies 

 inversely with the pressure of the gas, and concludes that this 

 law is true only within certain limited conditions. — Dante 

 Roster, remarks in connection with Prof. Mariacher's observa- 

 tions on the food of birds. These studies have a practical value, 

 tending to determine those birds which are insectivorous, and 

 consequently harmless, and those that are graminivorous and 

 injurious to the crops. 



Reali Istitiito Lombardo, January 7. — Summary of Tito 

 Vignoli's monograph on " The Psychic Act of Attention in the 

 Animal Series," in which the author describes the genesis of 

 attention from the lowest to the highest organisms, analysing 

 the elements of sensation and perception, and determining their 

 comparative values. The physiological and psychological con- 

 ditions of attention are held to be identical in the higher animals and 

 in man, differing only objectively, and man alone being capable of 

 introspective thought. Hence man is distinguished from other ani- 

 mals, not by the physio-psychic act of attention, but by the faculty 

 of submitting his own intelligence to examination. — In a supple- 

 mentary note on the transition from animal to human intelli- 

 gence, Vignoli argues that Darwinism will never succeed in 

 explaining the evolution of the organic from the inorganic, nor 

 of sensation and consciousness from the mere organic. The 

 passage from the intelligence of animals to that of man is not a 

 gradual development of the faculties, but is accomplished by a 

 reflex act of animal intelligence on itself. This act must be instan- 

 taneous, consequently is not the result of evolution, as are the 

 physical conditions leading up to it. 



SOCIETIES AND ACADEMIES 



London 

 Royal Society, January 7. — " Experimental Researches 

 on the Propagation of Heat by Conduction in Muscle, 

 Liver, Kidney, Bone, and Brain." By J. S. Lombard, M. D., 

 formerly Assistant Professor of Physiology in Harvard Univer- 

 sity. Communicated by Charles E. Brown- Sequard, M.D., 

 LL.D., F.R.S. 



January 14. — "Notes upon the Straining of Ships caused by 

 Rolling." By Prof. Francis Elgar, LL.D., F.R.S.E 



It does not appear that any serious attempt has yet been made 

 to investigate the amounts, or even the nature, of the principal 

 straining actions which the rolling of a ship brings into play, or 

 of the effect of those straining actions upon the material of 

 which the hull is composed. Various writers, from Bouguer in 

 1746, down to Prof Slacquorne Rankine in 1866, and Sir E. J. 

 Reed in 1871, have discussed the straining actions that are 

 caused by longitudinal racking and bending when a vessel is 

 floating in statical equilibrium. Sir E. J. Reed elaborately in- 

 vestigated the subject in a paper contained in the Philosophical 

 Transactions of the Royal Society for 1S71, and gave examples 

 of the amounts and distribution of the stresses caused by such 



straining actions in several typical ships of Her Majesty's Navy. 

 Mr. W. John supplemented this by a paper on the strength of 

 iron ships, read before the Institution of Naval Architects in 

 1874, in which similar results were given for_ various classes of 

 vessels in the mercantile marine. 1- "- 



The later investigations of these longitudinal straining actions 

 apply not only to the case of a ship floating in equilibrium in 

 still water, but also to cases in which she is (i) in instantaneous 

 statical equilibrium across the crest of a wave ; and (2) in in- 

 stantaneous statical equilibrium across the hollow of a wave — 

 the wave-length being equal to the length of the ship. 



Cases frequently occur which show that the maximum stresses 

 of the material of a ship's hull are not in proportion to the 

 results obtained by the ordinary calculations ; and that certain 

 deductions that have been drawn from those results are by no 

 means sound. For instance, it is said to follow from the analogy 

 between the longitudinal bending action upon a ship afloat and 

 that upon a loaded girder, that there is little or no stress exerted 

 upon that portion of a ship's plating which is in the vicinity of 

 the neutral axis for the upright position ; and the inference has 

 been drawn that, subject to the consideration of the sides being 

 occasionally brought, in some degree, into the positions of flanges 

 of a girder at large inclinations, the thickness of the material 

 may be decreased with advantage near the neutral axis. Now 

 it cannot be shown that the plating which is in the vicinity of 

 the neutral axis when the ship is upright, is ever brought into 

 such a position by the rolling of a vessel as to be much affected 

 by mere longitudinal bending. 



Other propositions respecting the distribution of stress in 

 various parts of the structure have been deduced from con- 

 siderations and assumptions upon which the ordinary calculations 

 of longitudinal strength are based ; and rules have, in conse- 

 quence, been proposed for regulating the strength of the prin- 

 cipal component parts of ships' hulls. It is only necessai'y here 

 to say that many of those deductions, like the one already 

 noticed, are unsound, and are not consistent with the effects 

 that may be observed of straining action at sea. 



A considerable experience at sea, where the author has closely 

 observed the effects of straining action caused by twisting 

 moments, and a further experience in investigating the stresses 

 to which the various portions of ships' hulls are subjected ac- 

 cording to the theories referred to, and in comparing the results 

 so obtained with the visible evidences of straining action, have 

 convinced liim that the stresses caused by twisting moments are 

 much greater than is generally supposed, and that no rules for 

 regulating the strength of ships can be satisfactory if based upon 

 hypotheses that exclude all practical consideration of twisting 

 moments. 



The straining action considered in this paper is that caused 

 by the twisting moments which operate when a ship rolls from 

 side to side, and which are caused by differences in the longi- 

 tudinal distribution of the moments of the forces that cause 

 rotation, and those which resist rotation. 



After describing at length the manner in which the twisting 

 moments may be approximately calculated, the author proceeds 

 to consider the amounts and distribution of the stresses upon 

 the material of the hull which are caused by a given twisting 

 moment : — 



We can learn something of the nature and distribution of 

 those stresses ; but, at present, their amounts cannot be calcu- 

 lated with any reliable approacli to accuracy. Experiments are 

 required upon the torsion of thin shells of various prismatic 

 forms in order to furnish the requisite data for dealing with so 

 complicated a case as that of a ship's hull. The difliculty of 

 obtaining exact data is very great ; but attention is drawn to 

 some of the general considerations which affect the twisting 

 moments and the distribution of the twisting strains and stresses 

 over a ship's hull ; and to the bearing which these have upon 

 the important practical problems that relate to the structural 

 strength of ships. 



The best data available for guidance in judging of the dis- 

 tribution of strain and stress due to twisting over the structure 

 of a ship are to be found in M. de Saint-Venant's investigations, 

 of the torsion of prisms.' 



The distribution of the torsional stresses over the transverse 

 section of a ship's hull is obviously different from the distribution 



* " Memoires pr^sentes par divers Savants \ I'Academie des Sciences 

 , de rinstitut Impe'rial de France," 'tcme 14, 1856. " Mdmoire sur la 

 t Torsion de Prismes, &c." Par M. de Saint-Venant," pp. 233-5C0. Also 

 I Thomson and Tail's " Natural Philosophy," vol. i., fart 2, sees. {59-710. 



