29b 



SCIENCE 



[Vol. XVII. No. 434 



years, by Holtzer, the St. Chamond and Firminy Companies, and 

 other French makers, of the hardened chrome-steel armor-piercing 

 projectiles having only small cavities (without which their pro- 

 duction would probably be practically impossible), is a remarkable 

 illustration of the control which has been acquired over the treat- 

 ment of steel, and especially of varieties, such as this chrome-steel, 

 to which a very exceptional degree of hardness may be imparted 

 without detriment to tenacity, by carefully elaborated processes of 

 hardening and tempering. Experience in the application of these 

 appears to have conquered, at any rate, in very great measure, 

 the originally considerable tendency to the retention of a state of 

 unequal tension by the finished material for long periods, and 

 the frequent yielding of the mass to the disruptive force thereby 

 exerted. 



In visiting, in 1886, the several works at and near St. Etienne, 

 where the chrome-steel projectiles were being produced (their suc- 

 cessful manufacture being then of comparatively recent date) Sir 

 Frederick saw, at more than one establishment, a large number 

 of projectiles which had sustained spontaneous fracture. In one 

 store where the finished shot were stacked, after the lapse of the 

 period during which the tendency to the development of cracks 

 •or to rupture was stated to diminish gradually, he saw the head 

 of one out of a pile of projectiles which had quite recently been 

 projected to a distance of many feet by the violent spontaneous 

 rupture of the metal. Instances of the development of flaws in 

 these projectiles are now, so far as experience at Woolwich goes, 

 exceedingly rare. 



The address next proceeded to point out the inaportance of rest 

 in bringing about a diminution, if not an entire disappearance, of 

 internal strains ; and he referred to the analogous case of steel dies 

 for coining. Sir Thomas Graham had written the president a 

 letter in 1885, in which he stated that, if kept in store a year or 

 two, these dies became less apt to crack when in use, and coined 

 more pieces than dies newly tempered. The more important 

 question of internal strains in masses of steel composing the tubes 

 or barrels of guns next received attention in the address. The 

 ■condition in which the steel might have been, in such instances, 

 when subjected to the action of the exploding powder charge, 

 iraay be illustrated by reference to the behavior some years ago of 

 ithe tube of a large gun, in which, after the third proof-round was 

 ■fired, a circumferential crack was found to have become developed 

 in the front threads of the breech screw. Upon removing the 

 jacket from the tube, the crack extended forward along the 

 chamber and into the rifling, and when the tube was placed in 

 the lathe with a view of cutting off the injured portion, the crack 

 suddenly developed itself with a loud report, and ran along to 

 within eight feet of the muzzle ; a spiral crack at the same time 

 ran completely round the tube, which fell in two upon removal 

 from the lathe. 



The tempering with oil hardening of steel guns has been de- 

 monstrated to result in the development of more or less severe 

 internal stresses in the mass, which can only be removed by sub- 

 sequent careful annealing ; and until this latter practice was largely 

 adopted, instances occurred from time to time at Woolwich, and 

 at other gunmaking establishments, of the fracture of tubes and 

 hoops of guns, either during their treatment in the workshop, or 

 when at rest, or when, in the built-up condition, they have been 

 for the first time exposed to the shock produced by the firing of 

 the gun. One effect which the oil-hardening treatment has occa- 

 sionally exercised in the case of particular qualities of steel is that 

 of developing minute fissures or cracks in the metal, either super- 

 ficially or in the interior of the mass. This could not be rectified 

 by any annealing process, and it is still a question, to be deter- 

 mined by the teachings of experience and the results of investiga- 

 tions, whether any definite or reliable modifications in the compo- 

 sition of steel used for guns, tending to secure the desked combi- 

 nation of hardness and tenacity, may not be introduced, with the 

 result that a method of treatment of the metal may be discarded, 

 which — however carefully applied, and however efficient the 

 means adopted for reducing or neutralizing any possible prejudicial 

 influence upon the physical stability of the parts of which a gun 

 is built up — carries with it inherent elements of imcertainty and 

 possible danger. 



Turning to another branch of this subject, the president next 

 dwelt upon the investigations of Mr. Thomas Turner and Mr. 

 Keep upon the influence of silicon and other impurities in cast- 

 iron, a question which Sir Frederick had taken up in 1855. The 

 work of Gautier, Ledebur, and others, based upon Turner's infor- 

 mation, and the investigations of German experimentalists, have 

 combined to establish on a sound footing the value of ferro-silicon 

 in connection wich the treatment of cast-iron. Jiingst's experi- 

 ments seem to indicate clearly the conditions under which silicon 

 will contribute to the production of dense and homogeneous cast- 

 ings. 



Sir Frederick then made some observations on the development 

 of the basic process, and also the effect of aluminum and of 

 manganese as alloys of iron. The question of nickel-steel also 

 occupied a good deal of the address, Sir Frederick giving an ex- 

 cellent resume of what has already been done in this direction 

 chiefly in connection with armor-plate construction. 



EPIDEMICS OF CHOLERA FROM 1830 TO 1890. 



Dr. Willoughbt, in a paper before the Epidemiological Soci- 

 ety of London, condensed in a recent number of the Lancet, after 

 alluding to the doctrine of epidemic influences, telluric and at- 

 mospheric conditions, and other unknown agencies, as at once 

 baseless and needless, and to the opposite delusion, prevalent in 

 the south of Europe, of its being infectious in the same sense as 

 small-pox, asserted that all the independent and scientific students 

 of the subject in Europe and America were now agreed that the 

 vehicle of contagion was contained, in the evacuations, that it was 

 thus carried by fomites as soiled clothing, etc., while persons suf- 

 fering from the disease, even in unrecognized and mild forms, 

 infected the soil and water of places through which they passed. 

 Insanitary conditions favored its development, but the most in- 

 sanitary towns — as Rome. Seville, and others — had escaped, since 

 they bad been provided with pure water supplies. 



The incubation period he believed to be, as a rule, from one to 

 two days, four being an ample limit for quarantine purposes. Its 

 transportability and conveyance wholly and solely by human in- 

 tercourse was proved not only by the progress of every epidemic 

 having followed the great routes of trade and pilgrimages, but by 

 the rapidity of this progress having corresponded to the facilities 

 for travel, whether by caravans, river boats, railways, or ocean 

 steamers, quoting in this connection Dr. de Renzy and others as 

 to the altered circumstances of travel in northern India; and he 

 thus explained the immunity of Australia and Chili, virtually the 

 most isolated communities in the civilized world. 



It was, he said, in 1821 that cholera, so far as was known, 'first 

 advanced from India westward, reaching Astrakhan in 1823, but 

 subsiding until 1827, when a fresh wave swept over Persia, enter- 

 ing Russia in 1839. In 1830-31 it was fomented by the war in 

 Poland; in 1831-32 it spread over the whole of Europe, and in 

 1832-33, over North America, lingering in each continent for about 

 two years longer. It was remarkable, and totaUy inconsistent 

 with the theory of conveyance by winds, that, though some cases 

 had ocoun-ed on board ships in the Medway as early as July, 1831, 

 it did not reach London till February, 1832, having effected a 

 landing at Sunderland and travelled via Newcastle, Edinburgh, 

 Glasgow, Belfast, Dublin, and Cork, whence it was at length 

 brought to London. 



A wave rolled over Persia, Arabia, and Syria between 1836 and 

 1839, but retired again. In 1840 it entered China, then passed 

 westward through Central Asia, re-entering India from Afghanis- 

 tan and through northern Persia, reaching the Caspian and Black 

 Seas in the summer of 1847. Following the military road then in 

 course of construction from the Caucasus to Moscow, and the 

 river highway of the Volga, it was intensified and spread by the 

 fair at Nijui Novgorod and the massing of the Russian, Austrian, 

 and insurgent Hungarian armies on the Danube, and in the course 

 of 1848-49 had attacked every country in Europe except Denmark 

 and Greece, which were saved by stringent quarantine. It ex- 

 tended to America in 1849, but died out in the course of the fol- 

 lowing year. 



