1839.] 



THE CIVIL ENGINEER AND AIICHITECTS JOURNAL. 



389 



\\a.s eiii))Io)e(l on many l)uiI(Uiigs lliiil alVuitlcd, more or Ictis, opportunities for 

 tlie display of talent, yet tlial wliicli ought most to liavc distinguislicd him, 

 it being entirely his own, namely HoNvning College, is by no means so crc<Ii- 

 table to his taste as the new screen at King's College. Besides these works 

 he made some additions at Corpus Christi and Trinity Colleges, and exeented, 

 we believe, some rejjairs at St. Mary's Cluireh, in that university, .\nolher 

 large pubhe building creeted by him is the East India College at llailejhury, 

 which, ho>\cver, does not say much for his invention, being not only in pre- 

 cisely the same style, bnt little more tlian a repetition or variation of his de- 

 sign for Downing, as was strikingly manifested by the two drawings at the 

 Exhibition in 1S38. I See our iirst volume, p. 221.) In the Nelson column at 

 Great Yarmouth he showed infinitely more originality, and he also designed 

 another memorial to the same hero, namely that in Sackville Street, Dublin. 

 Ill London he built the University Club House, the London University, St. 

 George's Hospital, and the National Gallery, all of ^\hieh are delineated and 

 described in the new editiim of the " Public iiuildings," by Mr. Leeds. 

 Though unlinished, and now perhaps never likely to he completed according 

 to the original design, the LTiiiversity is one of the happiest of his works, far 

 more so than tlie National Gallery, which seems hardly to he the production 

 of the same architect, the dome of the latter being as unsightly a feature in 

 composition, as in the other it is graceful. Perhaps Mr. 'Wilkins would have 

 earned nuich higher fame for himself, had not his study of, and unquestioning 

 reverence for antiquity, and the classical works of the Greeks, in some degree 

 fettered his ideas anrl lowered his ambition, preventing him from aspu'ing to 

 higher merit than that of merely applying correct imitations of Grecian orders 

 and porticoes to his own buildings, sometimes witlioiit even attempting any 

 thing fm'ther, as in the liouse at Osherton and Downing College. Ilis literary 

 productions, too, were quite as much archieologieal as architectural : they 

 consist of the following puhhcations : — .Vutiquities of Magna Gr.tcia, im]). fol. 

 Cambridge, 1807 ; Kemarks on the Tojiography and Ihiildings of Atliens, 

 roy. 8vo. 1810; The Civil Architecture of Vitruvius, 2 vols., imp. 4to. 1817 ; 

 I'rolusiones Architeetonica;, 4to. 1837. 



In his private character, Mr. Wilkins was a most amiable ami honoural)Ie 

 man, warm in temper, hut kind-hearted, affable, generous and liberal, without 

 the slightest tinge of that ostentation which sometimes renders pecuniary 

 liberaUty little better than pride and self-worship. Unlike his iiredeeessor 

 in office at the Academy, he was not given to make any parade of pidilie 

 donations, but his Uherallty was prompted by sincere hcnevolenee, and placed 

 beyond the suspicion of any unwortfiy motive. \Ve have heard anecdotes of 

 his kindness and generosity that reflect the highest honour ujion his memory, 

 and prove him to have been, what is infinitely superior to his highest title as 

 a scholai- or an artist, a tndy noble-minded and worthy man. 



Marine Railway Slip. — The Courrier de Bordeaia; contains a de- 

 scription of the marine railway, an apparatus introduced into France from the 

 United States, ami by means of which vessels of any size can he hauled ashore 

 in an upright position for the purposes of careening, &e. It will he remem- 

 bered that by means of this railway a vessel was hauled up and lowered agaui 

 the other day in presence of tlic Duke and Duchess of Orleans. It consists 

 of a railway, wliieh may he prolonged indefinitely muler the water to suit the 

 rise or fall of the tide, and also on shore, according to the size of tlie ship- 

 yard. Upon this an immense kind of wooden can'iage, proportioned to the 

 size of the vessel, is made to traverse by means of strong capstans. This 

 carriage is of such a nature that it can be got under the keel of the ship, or 

 rather the ship may be made to float on to it, and, by means of a system of 

 ■wedges and ropes, can thus he so adapted to the hull as to lit and embrace it 

 tightly all around. The sliip is kept in the jieiTiendiculai', either with or 

 without her cargo and crew on lioard, and the capstans being set to work, 

 the carriage and its biuden arc hauled up the railway at the rate of from two 

 to three feet per minute. The advantages of this system over that of dry 

 docks, or of laying a vessel on its side, are stated to he very great ; and a 

 great saving of time and money is also effected. It was brought into France 

 by M. I'lantevigne, of BordeaiLX, who has taken out a patent for if. 



*** Is not tliis marine railway, the same as Morton's jiatent slip, which 

 has travelled from England to America, and thence to France .' — [Editor C. E. 

 & A. Journal.] 



AN ARITHMETICAL BALANCE, OR NEW CALCULATING 

 MACHINE. 



By M. Leon Lalanne, engineer, "cles Fonts et C/mmres." Com- 

 municated to ine " Acadcmie des Scien<:e." at the silting on the '2nd 

 ultimo. 



In milking on estimate for the construction of an ordinary road, a 

 canal, or a railway, it is not sufficient to calculate the quantity of 

 ground work to be removed: but it is imporlant also to ascertain the 

 mean distance to which the cuttings have to be removed. For this 

 purpose it is requisite to employ a person will versed in calculation, 

 and particular care is required to avoid errors. 



The ordinary mode of proceeding is to divide the section into 

 lengths, and then to ascertain the cubical quantity of earth in each 

 division, aucl multiply it by the distance to wiiich it has to be le- 



11 Ihe products so found, ilividcd by the total 

 removed, gives for quotient the mean distance, 



ino\ ed ; the sum of 



quantity of earth to bi 



or lead. This operation, the author observes, is always excessively 



tedious. For example, a road i'oiu- kilometres ( ioT'l yards) in length, 



would be divided into about 100 spaces, of about 40 metres each, and 



each division would require two multiplications of numbers of between 



3 and 5 figures by numbers of 2 or 3 figures. 



Now if we compare the algebraic formula which represents tbe 

 method by which the average distance is determined with the relation 

 whicli exists between a system of parallel forces acting in the same 

 direction at diH'erent points of a lever, when they are in eciuilibrio, we 

 shall observe a striking analogy; for, calling j', p', p" — Ihe distances 

 from the fulcrum at wliich the forces P, P', P", are applied cm one of 

 tlie arms of the lever, and 5 the distance from the fulcrum to the point 

 where the force P-(-F"-|-P"+, equal to tlie sum of tlie former forces, 

 acting un the other arm, should be concentrated, we shall have 



,_ PP+P'P '+P"P"+-- 

 P+P'-f P"-f- . . 



Now this distance is precisely that which serves to determine the 

 mean distance of transport S of the volumes P, P', P". .removed re- 

 spectively to the distances p, p', p".. . 



So thai, to determine the mean distance of transport, without calcu- 

 lation, it suffices to suspend on one of the arms of a lever, W'hich 

 balances one its jioint of suspension, weights proportional to the 

 volumes to be transported, at distances from the point of suspension 

 proportional to the respective distances of transport; and to seek at 

 what distance on the other arm of the lever a weight equal to the sum 

 of Ihe former should be suspended, that the whole system may be in 

 cqiiilibrio. 



The machine presented to the Academy by the author is founded 

 on this principle ; it was constructed from his own designs, at the ex- 

 pense of the "administration des Ponts et Chaussees," by the cele- 

 brated optician, M. Ernst. It is in the form of an ordinary balance 

 without scales, of which the beam has a breadth of several centimetres. 

 The two arms of the beam are divided into equal parts on each side 

 of the axis of suspension, and one of them is divided into equal inter- 

 vals by small transverse ridges, between which are placed the weights, 

 which are in the form of flat plates. This simple arrangement over- 

 comes the diHiculty which it seemed would be met with in practice, 

 in cousecpience of having to fix a great number of ditlerent weights at 

 vai'ialjle distances and sometimes very near to each other. The total 

 weight suspended on the other arm is contained in a small moveable 

 scale. This instrument has 150 divisions on each side of the axis, in 

 a length of about 30 centimetres (12 inches); each division corres- 

 ponds to a distance of four metres (4-4 yards), so that the instrument 

 is capable of indicating distances of transport as far as GOO metres 

 (650 yards), which is never exceeded m the construction of an ordi- 

 nary road. The scale of weights is at the rate of one demi-centi- 

 grainme to a cubic metre. As the tiuantity of cutting is on an average 

 not more than 5, and never exceeds 20 cubic metres per metre run, 

 each arm of the balance will not, for a road four kilometres (4374 

 yards) in length, be charged on an average with more than 100, and 

 in extreme cases with 400 grammes at most. 



Since the apparatus gives the value of 5 in the general formula, 



S := PP+PV+P"P"+-- 



Q+Q'+Q"+-- 



in which the quantities P, P', P". .p, p', p". .Q, Q', Q". .may have 

 any finite value whatever, positive or negative, it may be employed 

 not only for the determiuatiou of means, and the solution of the rules 

 of alloys, but also for all the operations comprised implicitly in the 

 formula, as the rule of three, common multiplication and division, in- 

 volution, &c. It is even applicable to the calculation of terraces, 

 and may furnish the results very oxp^'ditiously. From trials which 

 have been already made, it is calculatuti that the mean distance may 

 be found by means of the machine in at most one-fourth of the time 

 required by the ordinary method. 



A very simple modification would render the arithmetical balance 

 available for calculations of a much higher orilcr. Thus, to obtain the 

 value of .1' in the formula. 



■ = A- 



b'^c^ 



it is sutficient, besides the graduation in equal parts, to add logarithmic 

 divisions analogous to those of Gunter's rules ; for the preceding ecpia- 

 tion gives 



a log A-|-6 log B+c log C-f- . . 



log a ' 



wliich indicates the equilibritim of a lever charged on one of its arraa 



