1850.] 



THE CiVIL ENGiXEEil AXD ARCHITECTS JOURNAL. 



303 



opinions of all my colleagues, the resident engineer and ship- 

 wrights ; the result, however, of the approximation which I vras 

 enaliled to effect, was so far satisfactory that of the two steamers 

 (])ropeller by sister engines), the larger of the two on these lines 

 proved mnch superior, both in speed, stability, and in fact in 

 every quality of a good passenger-boat, to the smaller lines of 

 which, for tlie sake of a fair trial of system, 1 accepted from the 

 Government Xaval Architect, giving my vessel purposely larger 

 dimensions, both as to lengtli and breadth, the vessels being 

 destined for the Bay, the direct resistance of the immersed mid- 

 ship sections being, however, the same in each; the advantage 

 gained in speed was as 7 to 8, and this superiority is since main- 

 tained : the sailing vessels also gave satisfaction, being reported, 

 after trial at sea, as very " superior sea boats," " stiff," and re- 

 markably easy under sail, neither pitching or 'scending in heavy 

 seas, although not very remarkable for "speed," (this quality 

 having been since obtained by alteration of masts and sails.) 



Encouraged by these results and having in the interim obtained 

 a copy of Mr. Fishbourne's very int. resting Lectures upon the 

 subject, 1 proceeded in May 1848, still in the face of great opposi- 

 tion, to lay down the keel of a small schooner of 123 tons, follow- 

 ing in this design the proportions recommended by Fishbourne. 

 The result was most satisfactory, being reported, after a four 

 months' voyage to different ports, to possess all the properties of 

 an excellent sea boat — speed, weatherly qualities, sufficient 

 hydrostatic stability, and great hydrodynamic (both longitudinal 

 and lateral) stability. The master expressing himself in the highest 

 terms of her performance, after paying proper attention to ballast- 

 ing and rigging, which was not done on leaving this port. The 

 result has been an order, for the government, of a similar vessel, 

 for a " guarda costa." About the same time I launched a steam 

 tug of 230 tons, and 90-horse power, destined for the heavy rolling 

 bar of Rio Grande; her lines were also assimilated as much as such 

 service would justify to the proportions recommended. She has 

 now been for some months on that dangerous station, giving great 

 satisfaction, having also made the shortest passage on record to 

 her place of destination, and having proved herself on her trials 

 here equal in speed to the largest steamboats of our packet 

 company. 



1 have lately launched the "guarda costa" (not yet tried), and 

 a small armed steamer, also for government (for river service and 

 drawing 42 inches of water), both built on wave principles, and of 

 which I take the liberty of enclosing the lines, as also of the 

 schooner, and a small steamboat for tlie use of the establishment. 

 The government steamer has just been tried, and I flatter myself 

 will settle the question here "as to Hues," her performance being 

 most satisfactory, overcoming the " resistances," imperceptibly 

 dividing and leaving the water almost without a ripple (at 10 

 knots), with very little power (two engines of 20-horse power, of 

 Miller's). My colleagues, however, are not yet convinced of the 

 advantages of the " full water line, aft, " insisting that the sharp 

 line would have still improved her. I must confess, myself, how- 

 ever, of your opinion, and I consider this as one of the most 

 scientific and valuable points of the theory. 



I am now engaged with two large steamers for government, one 

 of no tons well forward; the other of 560 tons, also laid down: but 

 as I have not been able to overcome the mistaken desire to place 

 very heavy artillery on the forecastles, 1 have been obliged to 

 adopt a rather fuller entrance line than 1 should have wished, ap- 

 proaching more to the wedge shape. Time however is required, 

 1 find, even in England, to overcome prejudices, so that we cannot 

 eixpect otherwise in these countries, wliere the sciences and arts 

 are in the hands of empirics, with a very few honourble e.xceptions, 

 and where we have not only prejudice but envious and interested 

 motives to combat. 



I should now crave your indulgence for occupying your attention 

 with these particulars; but 1 am persuaded that as the advance- 

 ment of science must be an object of interest to you, its progress 

 in this remote quarter will not be a matter of indifference as respects 

 the system of rather the relative proportions. 1 should wish to 

 offer to your consideration a few remarks, but cannot allow myself 

 this liberty until I have the pleasure of knowing that such oljser- 

 vations may not be considered presuming from a person who has 

 not the advantage of your acquaintance, but whose object is also 

 the development and progress of the arts, and w hose attention has 

 been long directed, and is now chitfiy devoted to the subject of 

 naval architecture. This being also his only excuse for the liberty 

 of addressing you. 



That the advantages which must certainly attend the introduc- 

 tion of the system may be attributed in this country to their ori- 



ginal proposer and distinguished advocate, I have further taken 

 the liberty of directing your name to be given and carved upon the 

 stern-sheets of a large passenger boat (lattern rigged) also built 

 here on your principles, and now plying ou our magnificent Bar, 

 bearing away the pain) from all competitors. 

 1 am, &c. 



Thomas Butler Dodgson, 



Naval Architect. 



On the Dynnmic Equivalent of Current Electricity, and on a fixed scale 

 /yr Electromotive lorce in Galvaiiometry. liy Mr. \V. Pktbie. 



The riynamic value of a current of voltaic electricity is represented by the 

 product iif the rate at which electrn-chemioal action is taking place at any 

 cross ser-tion of the current, (in other words, the quantity of the current,) 

 anrt the electromotive force with nhith the current is sustained, which may 

 be briefly teinied its energy or intensity, (provided the idea of quantity be 

 kept riislinct from this.) [he first object was to secure such units of cnni- 

 parison for both these tlements os should be at all times recoverable. This 

 is given in respect of quantity by the rate of chemical action, and the atomic 

 weights. Jti respi-ct of intensity of the current, we have no such fixed data, 

 and the intensity of most voltaic arrangements cannot be relied on as 

 constants for comparison. But tlie elements of Daniells' Battery, and those 

 of nitric acid batteries with negative surface of platinum, carbon, or cast- 

 iron, give an electromotive force or intensity that can be recovered witli 

 considerable exartitutle, if uniformity of circumstances, materials, &c. be 

 tolera ply attended to: these, therefore, may be used to give a fixed and 

 recoverable point in a galvancmetric scale of intensity. Now it so happens, 

 that if we assume the degrees of the scale to he of such a size that the 

 intensity of Daniell's (standard) elements shall be 60 of the degrees, 

 temperature being 70 Fahr. — that of nitric acid batteries will be from 100 to 

 112 of the same degrees ; the author, therefore, has always user! this sea!e, 

 to which all other voltaic arrangements can be referred. Which scale, he 

 would suggest, would be most conveniently used in assigning the electromo- 

 tive power of electric currents from any source. The mean result of careful 

 experiments, trifd directly and conversely, is that a voltaic current of one 

 unit in quantity, (or that frooi one grain of zinc electro-oxidizerl per minute,) 

 and of 100 degrees intensity, represents a dynamic force of 302^ pounds 

 raised one foot high per minute. This datum is of great interest as a 

 scientific truth in connection with the other correlative agents of nature, 

 (heat, electricity, light, and chemic.il affinities, neuralgic power, &c..) most 

 of which we may hope soon to see reduced to a mutually comparable rela- 

 tion to each other, in terms of the great centre and medium of comparieon, 

 mechanical foice. 



On the Chemical Composition of the Rocks of the Coal Formation. By 

 Mr. Henry Taylor. 



Mr. Taylor pointed out the analogies of constitution between certain 

 rocks, and referred to experiments made by him ou organic and inorganic 

 constituents. The author had in view the solution of the difficult problems 

 connected with geology, by facts deduced from chemistry; for instance, the 

 deposition of the stratified rouks as to their order, &e., by a process of 

 reasoning based on the composition of these rocks, and to this end he sub- 

 milled several analyses as a small contribution to our knowledge of the 

 rocks of the coal formation. Details of the analyses of fire-clay, specific 

 gravity 2519, good coal, specific gravity r2o9, coarse coal, specific gravity 

 1-269, bituminous shale, specific gravity 1-800, blue shale (slate-clay), specific 

 gravity 2-536, micaceous saudftone, specific gravity 2-598, muscle bind, 

 specific gravity 2 592, and of canuel coal, specific gravity 1-319, were given, 

 and a comparative view of the analyses seemed to suggest a pretty close 

 conuection between various members of the group, taken principally from 

 "Buddie's Ilaitley" colliery in the Newcastle coal field. The organic 

 matter iutermLxed with the various strata enclosing the coal appeared to be 

 of the same composition as the coal itself, except that its decomposition had 

 been carried further. The inorganic matter of these strata likewise evideiiCe 

 a close connection among them, though owing to the greater number of 

 constituents, this could not be so readily shown. Formulae for the t«o 

 classes of matter were given, and Mr. Taylor, in conclusion, hoped that the 

 results of bis analyses were sufficiently interesting to lead others into the 

 same field of inquiry, and eventually to a right appreciation of the laws 

 which regulate the deposition of the stratified rocks. 



Notice of the Working of the New Integrating Anemometer during tJie 

 past year. By Mr. Follet Osler. 



A sheet of plain paj/er placed in the instrument under a registering pencil 

 is moved forward by rotating hemispherical fans, at the rate of one inch for 

 every ten miles of air that passes; this same pencil, having a lateral motion 

 given to it by a vane, records the point of the compass from which the wind 

 blojfs, and a clock hammer descending every hour strikes its mark on the 

 margin of the paper to express the time. Thus, in a single line are given, 

 firstly, the length of the current ; secondly, the direction of it; and thirdly, 

 the time occupied in passing a given station marked houily or at any shorter 

 interval that may be desired. 



