264 REPORT — 1861. 



be determiuecl. Their results, in the exact form, are very complex ; but they can 

 be expressed approximately, for practical purposes, by comparatively simple rules. 

 Examples are given of the application of those rules to experiments by Mr. J. R. 

 Napier, the author, and others, on steam-ships of very various sizes,' forms, and 

 speed. 



The principal conclusions an-ived at are : — that friction constitutes the most 

 important part, if not the whole, of the resistance to the motion of ships that are 

 well formed for speed ; that its amount can be deduced with great precision from 

 the form of the ship, by proper mathematical processes ; that the engine-power 

 required to overcome it varies nearly as the cube of the speed, and as a quantity 

 called the "_ augmented surface," which is the quantity to be considered iu fixing 

 the dimensions of propellers ; that the friction consists" of two parts, one increasing 

 and the other diminishing with the length of the vessel ; that the least resistance 

 for a given displacement and speed is given by a proportion of length to breadth 

 which is somewhere about sei^en to one, and that excess of length is the best side to 

 en- on. The author states as limitations to his theory, that it does not give the entire 

 resistance of vessels that are so blufi" as to push before them or drag behind them 

 masses of " dead water," nor of vessels so small for their speed as to raise waves 

 that bury a considerable pai-t of their bows; and from the latter limitation he 

 deduces precautions to be observed in making experiments on models, in order that 

 the results may be applicable to large ships. 



Aj>pendiv to a Paper " On the Besistance of Shi2JS." 

 By Professor "W. J. Macquori^ Rankine, F.B.S. 



This appendix contains a comparison between the sailing yachts 'Themis' 

 (formerly ' Titania ') and ' America,' founded on their published plans. The author 

 shows, that although, from the gi-eater size of the * America,' and especially from 

 the gTeater area and breadth of her load water-line, her capacity for caiTying sail 

 must be greater than that of the ' Themis,' the " augmented surfaces " of those two 

 vessels are almost exactly equal ; so that, according to the theory set forth in the 

 paper, the ' America ' ought to be the more speedy vessel — a result agreeing with 

 that of the well-lmowu trial of speed. The " augmented surface " of the ' Themis ' 

 is increased by the veiy hollow foi-m of her cross-sections, so as to be greater than 

 it might have been, if those sections had been nearly triangular, as they are in the 

 * America.' 



On the Apjylication of WorlsJwp Tools to the Construction of Steam-Engines 

 and other Machinery. By J. Robinson, 

 The author made some observations upon the planing machine, the slide-lathe, 

 the screw-cutting lathe, giving any range of motion ; the radial drill, the slot drill, 

 the key grooving machine, the shaping machine, the bolt and nut cutting machine, 

 &c. The steam-hammer, the punching machine, the riveting machine, were also 

 dilated upon. The last-named was worked by hydraulic power, by Sir William 

 Armstrong. The export of machinery, from 1856 to 1860, amounted to £17,000,000. 

 No siich quantity of machinery could have been made and exported, he submitted, 

 had it not been for the important tools enumerated. 



On a System of Teleyraphic Communication adopted in Berlin in case of Fires. 



By C. W. Siemens, F.B.S. 

 By means of this an-angement, immediately after a fire occurred the police at every 

 station in the town could be informed of the occun-ence, and of the district iu which 

 the fire hadoccurred. lie said it was found by the adoption of this system that 

 the fire-engine was generally on the ground five minutes after the alarm had been 

 given. He also explained and exhibited a system of railway signalling extensively 

 adopted on the Continent, which rendered collisions almost impossible. This 

 system of fire-alarm telegraph was first established at Berlin in 1849, by the firm of 

 Siemens and ITalske, and has since been adopted at several other continental cities, 

 including St. Petersburg. 



