156 



THE CIVIL E.\(;iNE£K AND ARCHITECT'S JOURNAL. 



Ua 



speed was accurately ascertained. The force and direction of the wind was 

 ascertained by a wind gauge, placed 5 feet above the top of the carriage, 

 with the connections brought liown tn pencils which indicated on the same 

 sheet all the results. Indicator cards were also taken simultaneously from 

 the steam cylinders as frequently as was practicable, but not continuously, 

 as it was a service of some danger, tiie experimenter being obliged to sit on 

 the bulTer- beam of the engine at a velocity of 00 miles per hour, and in that 

 windy position to lake ort' four sets of cards in three quarters of a minute. 

 The spot selected for performing the experiments was one mile of railway 

 perfectly straight and level, and nearly on the surface of the ground ; and in 

 the plan the beiglit of the trees, hedges, and every intervening object which 

 could affect the influence of the wind is clearly marked. The experimental 

 train consisted of lirst and second-class carriages, each on six wheels, 4 feet 

 diameter, taken indiscriminately from the working stock, and loaded with 

 iron to represent a fair load of passengers, giving a gross weight for each of 

 10 tons. The experiments were tried with various weights and speeds up to 

 100 tons and to 02 miles per hour, and the results were classified and 

 arranged in a tabular form, with copious explanatory headings, so as to ren- 

 der reference to them exceedingly easy. 



The author first reviewed the deductions of Mr. Wyndham Harding's for- 

 mula, which was given at the discussion at the Institution in 1840, and gave 

 his reasons for dissenting from that formula. He then examined critically 

 several experiments recorded in the tables, stating candidly all the exceptions 

 that could be taken to them ; showing that although there was a difference 

 of as much as 52 per cent, shown between the resistance as calculated by 

 Mr. Harding's formnia and the experiments made by Mr. Gooch, that dif- 

 ference might be accounted for by the methods employed by Mr. Harding, 

 which were objected to, as calculated to produce erroneous results ; viz., 

 allowing carriages to run down inclines by their own gravity, using wheels 

 of 3 feet diameter instead of 4 feet, having a much greater length of train 

 for the wind to act upon, &e. He reviewed the great effect of a side wind 

 against a train — driving the flanehes of the wheels against the rails ; and 

 argued that the length of a train of carriages was much more important than 

 its own weight. The author did not offer any formula that should be appli- 

 table for calculating the resistance of all railway trains; but his tables gave 

 examples of almost every case that could occur, and thence data could be 

 supplied for those who wished to carry the investigation further, and make a 

 formula for themselves. He arrived at the conclusion that in practice the 

 friction of the axle-journals was not a constant quantity at all speeds, and 

 thought that the number and diameter of the wheels in a train, in proportion 

 to the weight, should form elements in any general formula. He showed by 

 experiments that the total atmospheric resistance to a train weighing 50 ton's 

 differed but slightly from that to a train of 100 tons weight, if the carriages 

 ■were small and the train long in the one case, and the reverse in the other 

 case. 



The general resuU of the diagram of resistance with trains of 100 tons and 

 with 50 tons showed that the resistance calculated by the narrow-gauge for- 

 mula with a 50 ton train, at G2^J miles per hour, was 37 lb.; with a train of 

 100 tons, by the same formula, at 01 miles, it was 311 lb. The broad gauge 

 resistance, with a train weighing 50 tons, at G2J miles per hour, was under 

 23 lb. ; and with a train weighing 100 tons, at 01 J miles per hour, was 22J 

 lb. We cannot, of course, give fully the lesults, except in a comprehensive 

 form, but such were tlie general results. 



The author concluded his paper by saying that it appeared to him neces- 

 sary, before any general formula for calculating the resistances to railway 

 trains could be made, that the value of the following elements, necessary In 

 such formula, should be determined by experiments : — 



1. The axle-journal friction, at different velocities and with different 

 weights, per square inch of journal surface. 



2. The resistance to the rotation of the wheels and axles per pair at dif- 

 ferent velocities and with different diameters. 



3. The resistance due to the rolling of the wheels upon the rails, with dif- 

 ferent weights upon them, and with different diameters. 



4. The resistance due to the passage of (he train through the atmosphere, 

 at different velocities, with different proportions of weight, and length and 

 breadth of train. 



5. The resistance due to the oscillation or unsteady motion of the train, 

 at various speeds. 



The author considers that all these values might be determined with a 

 considerable degree of accuracy, by careful experiment. 



SOCIETY OF ARTS, LONDON. 



April 12.— Sir ,J. \'. Boileau in the Chair. 

 Mr. DiGiY Wyatt, architect, read a paper " On the Art of Enamel, An- 

 cient and Modern." 



The paper commenced with some remarks on the necessity of increasing 

 the resources of the designers of uiilal work, by eliecting changes in the 

 process of manufacture; and by that act, producing a novelty which 

 might possess all the charm of freshness, without any of that exirava. 



gance so constantly resorted to in the attempt to produce variety. The 

 art of enamel presented this so much wished for desideratum, whereby 

 by imitating the practice of the mediaeval artists in this material, we 

 might considerably enrich our industrial resources, and facilitate the exe- 

 cution of beautiful works of utilitarian art. 



After a hasty description of the composition of pure enamel, and the 

 nature of the pigmeuts usually employed to colour it, Mr. Wyatt pro- 

 ceeded to enumerate the six leading varieties which had been adopted, at 

 various periods in the history of the art, to unite the vitreous paste with 

 its metallic base ; endeavouring, as far as possible, to describe each genus 

 in tile language of some contemporary authority. The first, or Byzantine 

 process, which obtained throughout the Eastern empire, from probably 

 the time of Justinian, down to about the year 1300, was illustrated from 

 the particulars furnished by Theophilus, the celebrated artist monk of the 

 11th or 12tli century; and its chief peculiarity appeared to have been the 

 formation of casements, or cavities, for the reception of the enamel, by 

 means of gobi filigree. 



The second, or early Limoges style, which was so much practised in 

 that city, from probably the 11th century, until the frightful siege and 

 massacre by the Black Prince, was described from a comparison of the 

 admirable notices of Mr. Albert May with those of MM. Petit, Dussieux, 

 Pottier, and tlie Abb^ Texier; and would seem to have substituted for the 

 filigree compartments of the Byzantine mode, iucisions in the thick cop- 

 per plate by the graver. 



The third, or early Italian mode, practised for probably some 50 years 

 before the days of Ugolino Veri, the artist who executed the celebrated 

 shrine in Oevieto Cathedral in the year 1338, and carried on by subsequent 

 goldsmiths and enamellers down to the end of the lOlh century, was detailed 

 from descriptions given by Vasari and Benvenuto Cellini; about the 

 middle of that century it appears to have held a midway position between 

 the ancient champ lere, or incised, and the painted enamels afterwards 

 produced, consisting in engraving silver after the manner of medallic relief, 

 and then floating it over with variously coloured transparent pastes. 



Benvenuto was said to have, if not invented, at least been the first to 

 describe the improvement that took place about the beginning of the 16th 

 century, in the art which constituted what Mr. M yatt called Jeweller's 

 enamel. It consisted in using as a vehicle, with the glass powder employed 

 to cover small gold or silver objects in the round, or in the highest relief, 

 water in which pips of pears had been steeped. This held the paste in 

 its place until vitrifaction took place, and was yet so delicate a cement, as 

 in no degree to interfere with the perfect purity of the enamel. 



The fifth, or " late Limoges" variety, was described as having sprung 

 at once, fully armed, from the brain of that Jupiter of enamel workers, 

 Leonard Limousin, under the auspices of Francis the First, and differed 

 from its predecessors chiefly in covering the entire surface of the metal 

 with an opaque paste, and then painting on it with transparent colours ; 

 regaining the efi'ect of a translucent ground by applying silver leaf in par- 

 ticular situations, fastening it with a glaze of colourless enamel, and then 

 tinting over it. These peculiarities, as well as the pcinture grisAtre, 

 and touching with gold, were illustrated from the interesting manuscripts 

 published by M. Maurice Ardent, of Limoges. This style appears to 

 have dwindled into nonentity under the hands of the Nouailhers, a family 

 who lived (they can scarcely be said to have flourished) during the latter 

 part of the 17th century. 



In connection with the detail of the sixth and last process — the Miniature 

 style — honourable allusion was made to the labours of Sir Theodore de 

 iMayerue (whose interesting manuscript we may shortly hope to see pub- 

 lished under the auspices of Mr. Heindrie) and his connection with Petitot, 

 the principal and best known of this school of art. The improvements 

 effected in this style would seem to h.ive been a great enrichment of the 

 palette, by the addition of new pigments, the power of multiplying the 

 number of firings, and graduating the succession of tints, tiieir hardness, 

 and fusibility, by the addition of fluxes, etc. Unhappily, the mystery 

 many selfish artists have throvyn over their modes of procedure, renders 

 them exceedingly difficult to analyse or describe. 



Mr. Wyatt then commencing with Egypt, gave a rapid sketch of the 

 history of the art, noting the barbaric enamels existent in the North, 

 probably previous to the Norman conquests; touching on the connection 

 between the Limoges and Byzantine schools; and tracing, though neces- 

 sarily very briefly, all the salient points in its existence, both as a manu- 

 facture and as an art, in our own and other countries. He glanced at 

 what had been recently done in the off /iers of Wagner and Ruilolph, at Paris, 

 and the exquisite paintings of Messrs. Bone and Essex ; and concluded by 

 expressing an earnest hope that the kno\^'ledge of art possessed by those 

 gentlemen might soon be grafted on the skill of our workmen, and that 

 we may ere long adopt, and fully carry out, the old practice of the middle 

 ages, so ably characterised by the Abbe Texier, in his eloquent declara- 

 tion that, " in those days, Art and IMauufactures were blended and iden- 

 tified ; Art gaining by the alfiuily great practical facility, and Manufac- 

 ture much original beauty," 



Sash Line. — Messrs. Newall and Co. have greatly improved their patent 

 copper wire cord, utiicti is now made extrenit'ly flexitJe. luid is well adapted tor window- 

 sash- line, hothouses, lightning eondiictors, picture-cord, cloclt-cord, bell.tianginp, and 

 many ottier purposes lor uiiich hempen rope has hitherto l)eeii used ; the advantages 

 being that it is cheaper, much more diiraljle, and one-sixth part the bullc ot hempen rope. 



