1846.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



55 



blish its merits as a powerful, econoraical, and durable engine, equal in 

 point of efficiency to any reciprocating engine in Her Majesty's service. 



Sliould additional evidence be sought to establish further claims as a 

 rival in steam mechanism, it is to be found in the simple fact, that this first 

 essay on the Earl of Dundonald's principle, although at first altered and 

 mutilated to bring it to perfection, is nevertheless at the present time per- 

 fectly free from those indications of weakness and declining energy wliich 

 any other engine, under similar circumstances, might probably evince, as 

 ii proved by its exhibiting a vacuum at all times equal to 2S inches of mer- 

 cury. 



Another fact which gives great confidence in the utility and applicability 

 of this principle is its freedom from liability to internal derangement, and 

 consequently tlie service in v\hich it is engaged is scarcely ever incon- 

 venienced by stoppages. 



The engine has not been opened for examination since July last. 



R. Taplin, Engineer and Machinist. 



Her Majesty's Dockyard, Portsmouth, Dec. 31, 1845. 



ARTIFICIAL ULTRAMARINE. 



Till within the last twelve or fifteen years the only source of this beati- 

 liful pigment was the rare mineral, /ayns lazuli. The price of the finest 

 ultramarine was then as high as five guineas the ounce. Since the njode 

 of making it artificially has been discovered, however, its price has fallen 

 to a few shillings the ounce. Artificial ultramarine is now manufactured 

 to a very considerable extent on the continent, but, as far as I can learn, 

 none has as yet been made in Great Britain. The chief French manu- 

 factories of ullraniarine are situated in Paris ; and the two largest ones in 

 Germany are those of Meissen in Saxony, and of Nuremberg iu Franconia. 

 Three kinds of ultramarine occur in commerce, the blue, the green, and 

 the yellow. The two first only are true ultramarines, that is sulphur com- 

 pounds ; the yellow is merely chromate of baryta. Both native and arti- 

 ficial ultramarine have been esamined very carefully by several eminent 

 chemists, who, however, have been unable to throw much light upon their 

 true nature. Chemists have undoubtedly ascertained that ultramarine 

 always consists of silica, alumina, soda, sulphur, and a little oxide of 

 iron, but no two specimens, either of tlie native or artificial ultramarine, 

 contain these ingredients in at all similar proportions. . . The last 

 chemist who has examined ultramarine is Dr. Eisner, who has published 

 a very elaborate paper upon it in the 23rd number of Erdmann's .Jour- 

 nal for 1841. The first part of Dr. Eisner's paper is historical, and con- 

 tains an account of the accidental discovery of artificial ultramarine bv 

 Tassart and Kulhman in 1814, and of the labours of subsequent chemists. 

 He then gives a detaded account of his own experiments. . . Dr. 

 Eisner's paper does not, however, furnish any details by which ultrama- 

 rine could be manufactured successfully on the great scale. Tlius, for 

 example, in regard to the necessary degree of heat, perhaps the most im- 

 portant circumstance in the process, he gives no directions whatever. W'e 

 know, however, from other sources, that it should be a low red i)eat,asatmuch 

 higher temperatures both native and artificial ultramarine soon become colour- 

 less. Dr. Eisner, indeed, does not allirni that be was able to procure ul- 

 tramarine in quantity of a uniformly good colour. In fact, the process of 

 Robiquet, published nearly ten years ago, is the best whicii scientific che- 

 mists possess, though undoubtedly the manufacturers have greatly im- 

 proved upon it. Robiquet's process consists in heating to low redness a 

 mixture of one part porcelain clay, one and a half sulphur, and one and a half 

 parts anhydrous carbonate of soda, either in an earthenware retort or co- 

 vered crucible, so long as vapours are given off. AV hen opened, the cru- 

 cible usually contains a spongy mass of a deep blue colour, containing 

 more or less ultramarine mixed with the excess of sulphur employed, and 

 some unaltered clay and soda. The soluble matter is removed by wash- 

 ing, and tlie ultramarine separated from the other impurities by leviga- 

 tion. It is to be regretted, however, that the results of Robiquet's pro- 

 cess are by no means uniform ; one time it yields a good deal of ultrama- 

 rine of excellent quality, and perhaps, at the very next repetition of the 

 process in circumstances apparently similar, very little ultramarine is ob- 

 tained, and that of an inferior quality. The fabrication of ultramarine is 

 a subject whicli well deserves the attention of English chemical manufac- 

 turers, as it could be carried on with peculiar advantage in this country. 

 The chief expense of the process is the fuel required, which can be pur- 

 chased in Great Britain for less than half the money it would cost either 

 in France or Germany, — Proctedinga of the Glasgow Philosophical So- 

 ciety. 



The Nelson Monument.— The completion of this work has at length 

 been determined on by the Woods and Forests, and to this effect a communication has 

 been made to the artists to wlioin the commissions have been confided, by the Earf of 

 Lincoln. The subjects proposed for the four bassi reiievi are the victories of Cape St. 

 Vineent, Copenhagen, the Nile, and Trafalgar; and the sculptors appointed to execute 

 these worlfs are Mr. Watson, Mr. Woodington, Mr. Carew, and Mr. Tmnouth. The 

 four lions will be executed fay I\Ir. Lough. The relieved works will be in bronze— the 

 lions in stone or granite. — " Examiner." 



PROCEEDINGS OP SCIEWTIPIC SOCIETIES. 



ROY.\L SCOTTISH SOCIETY OF ARTS. 



S. Mackenzie, Bart., of Coul, F.R.S.E., 



Monday Jan. 12. Sir Geo. 

 President, in the Chair. 



The following communications were made: 



1. " A Development of the o;jeralion of the Harmonic Patios m a pro. 

 gressive series of Scalene Triamjles, and of their effect upon the nectanglen 

 which these Trianc/les produce, by the nnion of their hypothenuses ; with 

 Remarks upon tij utility of such a series in an .iJslhetical point ofviev:. 

 By D. R. Hay, Esq.— Mr. Hay, in reading this paucr on the harmonic 

 ratios, exhibited by drawings, made in presence of the meeting, their ope- 

 ration, by a natural process, in producing a series of scalene triangles having 

 all the harmonic properties in relation to form, that the natural diatonic 

 scale of music has to sound. He showed that the beauty of proportion and 

 symmetry depends upon the operation of the numbers 2, 3, and 5, and that 

 theee numbers operate in the formation of geometrical figures by the division 

 of the circle into 3G0 degrees; asserting that no other mode of division 

 would produce the same results, because that number is in a peculiar manner 

 (which he also exhibited to the meeting) a multiple of those three harmonic 

 numbers. He also showed that, by the combinations of the scalene tri- 

 angles resulting from liis process, a series of rectangles was produced, and 

 proved that these rectangles had peculiar harmonic qualities, that belonged 

 to no other figures of the same species. He stated that such a scale was 

 a desideratum in architecture, and that its adoption would be attended with 

 incalculable advantage in that as well as in every other art in which form was 

 treated in the abstract. He also mentioned that his scale of harmonic forms 

 was applicable to curvelineal as well as rectilineal figures, and tliat he was 

 engaged in a work in which this should be proved. 



2. Description and Drawings of a Circular Saw for general purpose», hut 

 more particularly for Agriculturists. By Capt. G. D. Paterson.— This 

 saw, it was stated, is adajited both for cross-cutting and all other kinds of 

 work, but more particularly for running cuts through Ijattens, deals, cS:c., and 

 can travel through timber of any length. In cross-cutting, the workmen 

 can cause the saw to advance or retreat by means of a handle. For long 

 work the saw is driven backwards and forwards by machinery. Captain 

 Paterson adopted the plan of making the saw travel instead of ttie wood, not 

 only because liy that means greater precision is obtained than by moving the 

 wood to the saw (which indeed, in cross-cutting large trees is almost im- 

 practicable), but also in order to avoid the risk of crippling the saw, which 

 he had often known to occur from careless or inexperienced workmen twist- 

 ing the wood in the act of cutting. The saw is driven by belts. 



3. Description and Drou^ings of a Railway Indicator. By William An- 

 derson, mail-guard. — The machine, as it has been in action for three 

 months past on the Dundee and Arbroath Railway, was exhibited. The 

 indicator shows, at any moment, the number of miles the train has travelled 

 from the station at which it started, as well as the number to travel to the 

 end of the journey. It also enables the engineer or any other person in the 

 train to ascertain at night or in dense fogs, within a few' feet of the particular 

 spot on the line upon which the train is travelling. It also tells the rate of 

 speed, and the difl'erent stations and localities which the train passes ; and 

 also the hour and the length of time it takes to run every mile. It was stated 

 tliat it would be an eft'ecfual check to careless or reckles's driving, and would 

 be also a complete check upon book-keepers, conductors, and every other 

 servant connected with the train, as at the end of the journey it has only to 

 be examined in order to show the time when the train started — when it 

 reached every one of the dilierent stations — and the precise speed at which 

 it had travelled during any part of the jrmrney ; and were its indications 

 copied into a book, this would form a complete and lasting register of the 

 whole working on the line. 



-•/ tail Signal Light, to be attached to the upright spindle of the indicator, 

 was also described, viz. a revolving red and white light, which would show 

 at night the speed of a train in advance of another at a distance of four or 

 five .miles, and thus enable the driver of the following train to keep at a 

 proper distance from the one in advance. 



4. An antique calnnet Lock and Key of curious and ingenious worhnanship 

 was exhibited by Adam Gib Ellis, Esq., W.S., F.R.S.S.A. 



5. AModelofMt.'W. G. Cover's Removeal/le fVindow Sashes for the more 

 easy and safe 7neans of Cleaning IJ'indows entirely within the apartment. — 

 The advantages of the invention are stated to be, that the iron corner-pieces 

 strengthen the sashes, and render them removeable, and capable of being 

 taken inside the apartment to be cleaned. They also cause the sash to slide 

 more freely and silently in the frame; and when closed, the win'ow is per- 

 fectly firm, and free from any rattling or vibration. They can be applied 

 either to new or old windows at a cost of lUs. per window. 



ARCHAEOLOGICAL INSTITUTE. 



January 9. — Sir Richard Westmacott in the Chair. 



The increasing number and interest of the communications submitted to 

 the Institute has induced the Committee to devote two meetings in each 

 month solely to the exhibition of antiquities, and to archa;ological discussion. 



