October 3[, 1890.] 



SCIENCE. 



245 



In 1867 the British Government built the " Water Witch," a 

 1200 ton vessel, to test the value of hydraulic jet-propulsion. En- 

 gineering records show that several jet steamers have been built 

 since that date; the latest being the " Duke of Northumberland," 

 completed in.l!^90 for life-saving purposes. 



It is now well known that theorists were wrong in their con- 

 ceptions of the eflSciency of a jet. The eminent authority, Mr. S. 

 W. Barnaby, has shown that the efficiency of the jet is 75 per 

 ■cent, as against 05 per cent for the screw: in other vpords, it is 

 15 per cent belter than a remarkably efficient screw. Why, then, 

 has not the jet entirely superseded the screw? Mr Barnaby has 

 shown that it is due to pump inefficiency. This is a loss which 

 may be reduced, but cannot be entirely avoided. Friction and 

 inertia in the pump more than neutralize the enormous advantage 

 possessed by the jet over the screw. The average pump loss is 

 about one-half the total power. 



Mr. R. H. Tucker of Boston, in 1880, tried direct-air propulsion 

 on a canal- boat. An 8-horse-power engine drove a No. 4 Root 

 blower, the air being discharged directly against the water astern. 

 The Root blower has an efficiency of about 75 per cent. The re- 

 sult, four miles per hour, showed a good efficiency for the fuel 

 expenditure. 



As a whole, the Secor system provides those thermo-dynamic 

 •conditions which science demands, but which cannot be satisfied 

 in a reciprocating, rotating lieat-engine. In every known method 

 of propulsion, wliether paddle, screw, or jet, there is a considera- 

 ble expenditure of power between the cylinder and the propeller. 

 In the Secor system, friction and inertia of moving parts are 

 eliminated, and, without antei-ior loss of heat or power, that 

 method of propulsion is adopted which is suggested by the most 

 advanced science. 



The purpose of the present paper is to state briefly the theory of 

 the system rather than to discuss its commercial or naval advan- 

 tages. It may, however, be mentioned that a flrst-class transat- 

 lantic steamer carries a weight of 5,500 tons in engines, boilers, 

 fuel, and water. To offset this peraianent ballast, there is the 

 passenger accommodation, and capacity for less than 1,000 tons 

 of paying freight,— $10,000 in coal, about $600 in oil, -and 180 

 men are required to keep the leviathan in motion for one trip. 

 In view of this situation, the advantages of the Secor system, in 

 theory at least, are evident. 



NOTES AND NEWS. 



The eighth congress of the American Ornithologists' Union 

 Avill convene in Washington, D.C., on Tuesday, Nov. 18, at eleven 

 o'clock A M. The meetings will be held at the United States 

 National Museum. The presentation of ornithclogical papers will 

 form a prominent feature of the meetings; and meaibers are 

 earnestly requested to contribute, and to notify the secretary in 

 advance as to the titles of their communications, so that a pro 

 gramme for each day may be prepared. The address of the sec- 

 retary is John H. Sage, Portland, Conn 



— Platinum has long been recognized as an extremely refractory 

 metal to use in electroplating, the difficulties maioly arising from 

 the fact that the strength of the bath cannot be maintained, as 

 "with other metals, by using a plate of platinum as the anode, as 

 the metal will not dissolve. The consequence is, that both the 

 richness and conductivity of the bath are continually altering, 

 and a satisfactory deposit can only be obtained by the most con- 

 stant attention. In a recent paper on the subject which was read 

 before the chemical section of the Franklin Institute, according to 

 Engineering of Oct. 10, Mr. William H. Wahl states that it oc- 

 curred to him that it might be possible to maintain the strength 

 of the batli by greatly increasing the surface of platinum at 

 the anode, which was accomplished in the following way: a 

 plate of carbon was saturated with platinic chloride and dried, 

 thus impregnating the plate with the salt, from which the plati- 

 num was finally reduced to the metallic state by heating the whole 

 plate in a crucible. In this way a deposit of platinum in an ex- 

 tremely fine state of division was obtained in the pores of the 

 carbon plate, and this plate was then used as the anode of the 

 electrolytic bath. On passing the curi-ent, the platinum proved 



to be readily soluble in a bath of hydrochloric acid, and so far the 

 experiment was a success; but the process proved useless from a 

 commercial point of view, as the metal still remained insoluble 

 when the bath consisted of oxy salts of platinum, which alone 

 give good deposits. It was therefore necessary to devise some 

 other plan, and after many fruitless experiments Mr. Wahl claims 

 to have succeeded by using platinum hydroxide for maintaining 

 the strength of the metallic solution. For this purpose the salt, 

 which is readily soluble in alkalies and in many of the acids, may 

 be introduced into the plating bath from time to time, and dis- 

 solved therein by stirring; or it may be permitted to remain in the 

 bath in excess, either at the bottom or suspended in a canvas bag 

 adjacent to or surrounding the carbon anode. A weak aqueous 

 solution of caustic soda or caustic potash, especially the latter, will 

 dissolve a large quantity of platinum hydrate; and the solution 

 has the advantage of being freely conductive of electricity, and of 

 yielding bright, regular, and adherent deposits of platinum on 

 electrolysis. Further, with currents of moderate strength, the 

 platinum hydrate only is affected ; and hence the constitution of 

 the bath can be easily maintained constant by adding fresh sup- 

 plies of platinic hydrate. Other solvents have also been tested by 

 Mr. Wahl, but for these details we must refer our readers to his 

 paper, contenting ourselves with giving the main outlines of his 

 discovery. 



—The United States Coast and Geodetic Survey Office has re- 

 ceived from the Government Printing Office Appendices Nos. 12 

 and 13 to the "Report of the Superintendent for 1888," in pam- 

 phlet form. Their titles are "No. 12. Hypsometry: Heights from 

 Geodetic Levelling between Arkansas City, on the Mississippi 

 River, and Little Rock, Ark., 1887-88 (field-work by J. E. Mc- 

 Grath, sub-assistant; reduction by C. A. Schott, assistant);" 

 "No. 13. Astronomy: Differential Method of computing Star 

 Places," by E. D. Preston, assistant. The levelling-work in Ar- 

 kansas was continued in 1889 by Sub-Assistant Isaac Winston, 

 who ran the line from Little Rock, Ark., to Fort Smith, Ark. 

 Mr. Winston will probably extend the same work during the 

 coming season, beginning at Fort Smith, Ark., and running 

 northward toward Kansas City, Mo., where eventually this line 

 will be connected with the main transcontinental line of levels. 

 The results that are now being obtained are immediately utilized 

 by the Arkansas Geological Survey and others. 



— A meeting of a committee of Harvard students lias been held 

 to consider the best means of raising a fund for building a new 

 library reading-room. For several years students and instructors 

 alike have felt the need of such a room, cajjable of being lighted 

 and open in the evening. Two years ago a petition signed by 

 nearly every student of the university was presented to the cor- 

 poration, asking to have Gore Hall lighted by electricity. The 

 corporation deemed this unsafe, since the present building is not 

 flre proof; and impossible, since tliey had not the funds necessary 

 to make it fire-proof. To a letter asking what the cost of such a 

 reading room would be, the president replied, " A proper reading- 

 room attached to the present library building would cost from 

 $100,000 to $200,000, according to its size and general style. A 

 plain stone building of sufficient size, made fire-proof and lighted 

 with electricity, could hardly be built and furnished for less than 

 $100,000. If the design were elaborate and handsome, as well as 

 sufiiciently spacious, it could not be built for that sum.'" Ill ven- 

 tilation, bad light, and early closing of the library, together with 

 the feeling that no remedy was forthcoming, brought the matter 

 forcibly before the students. The committee above referred to 

 considered the advisability of taking active steps in the matter, 

 and voted to make a canvas of the college in order to raise as 

 large a portion of the fund as possible among the students them- 

 selves, and then, by a circular letttr, to appeal to the alumni for 

 the rest. Accordingly the college has been canvassed; and, not- 

 withstanding the many demands upon the students for money 

 consequent upon the opening of a new coUege-.i ear, 789 men have 

 already contributed $3,530, or $4.40 per man. According to the 

 last quinquennial catalogue, there are about 5,500 living grad- 

 uates of the college proper. It is to be hoped that from so large 

 a number at least $150,000 will be speedily forthcoming. 



