151 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[May 



The Namur is a six-wheeled engine, with the whole of the working 

 parts ouiside. 



Diameter of the driving wheels . . . 7 U. in. 



do. supporting do. . . . 3 ft. 'J in. 



Distance between centre of the extreme wheels 13 ft. in. 



Diameter of cylinder Oft. 10 in. 



Length of stroke ft. 20 in. 



Number of tubes ..... 182 



Length of ditto lift. in. 



Diameter of tubes, oatside . . . . ft. 2 in. 



Length of lire-box 4 ft. 3 in. 



Breadth of ditto 3 ft. .i in. 



Area of lire-grate 14 ft. ti in. 



Surface in lire-box . . . . . (i:! ft. in. 



Surface of tubes, inside .... 927 ft. in. 



Total surface 9H9 ft. in. 



This engine is constructed for the Namur and Liege Railway, and has run 

 on the London and North Western Railway, with every variety of train, a 

 distance of 2300 miles. In the course of the experiments the following 

 speeds have been reached :— With a train of trucks loaded with coke, and 

 weighing 80 tons, exclusive of engiue and tender, 51 miles per hour on a 

 level;— with a train weighing 50 tons, 62 miles per hour was attained, 

 between Tring and Wolverton. But the most severe test an engine can be 

 put to is when it has no train behind it: an experiment of this kind was 

 tried with the Namur,— Capt.Addington, inspector general of railways, 

 and Capt. Simnionds, his assistant, being on the engine at the time, with 

 which a speed of 75 miles an hour was attained on level ground, going 

 round a curve between London and Harrow. The speed was taken by 

 Captains Addington and Siramonds, and both were perfectly satisfied with 

 its steadiness at that rale of speed. A second engine is building for the 

 North Western Railway with 8 feet driving wheels.— The author concludes 

 by oafering, at an early date, to furnish an account of the expense of work- 

 ing the engine, and the consumption of coke, water, &c. 



Mr. Harding observed that Mr. Crampton had done perfectly right by 

 increasing the dimensions of the fiie-grate, for while the heating surface 

 of the ordinary engines has been quadrupled, the firegrate has not been 

 increased 30 per cent. He considered that the experiments, as far as they 

 had gone, were quite satisfactory. 



Mr. M'CoNNELL considered that the engine had performed very well,— 

 and that Mr. Cramplon might congratulate himself on having lowered the 

 centre of gravity, and increased the area of the fire-bars and the size of 

 the driving wheel. 



April 14.— Thomas Winkworth, Esq., in the Chair. 

 The secretary read a communication from Mr. W. C. Fuller, on his 

 " Vulcanized India-Rubber Buffers for Railway Carriages." The invention 

 consists in substituting a series of rings of india-rubber, separated by iron 

 plates, for the ordinary spiral spring. The buffer-rod passes through the 

 centre of the rings, and is protected from being bound by the india-rubber 

 when compressed, by means of a conical flange affixed to the iron plates. 

 The advantages which this invention appears to possess over the ordinary 

 springs are— great reduction in weight— less liability to get out of order- 

 greater facility of increasing or decreasing the power of the spring— and its 

 ready applicability to carriages already constructed, without increase of 

 cost. 



Mr. RicARDo wished to know what would be the compression of the 

 buffer under ordinary circumstances— supposing the length of the india- 

 rubber employed to be 3 feet ! 



Mr. Fuller stated, that the length of stroke required for the buffer is 

 from 10 to 13 inches ; that the ordinary strength of the pressnt springs is 

 from 3 to 3J tons ; that is, S tons reduces the circular spring to a flat, 

 while the India-rubber is capable of resisting from S to 50 tons. 



The next communication read was by Mr. Philip Palmer, " On the 

 Application of Crown (ilass Metal to the Manufacture of various Domestic 

 and other Articles."— The author commenced his paper by stating, thai he 

 did not intend, on the present occasion, to claim the attention of the Society 

 to works of art in glass, but to such as are of recent manufacture, and 

 have arisen out of the repeal of the duty on that material. Before the re 

 peal of the duty, crown glass was only used for glazing windows and for 

 prints, while the various articles for the table were made from flint glass. 

 After describing the difference of manufacture employed in the crown and 

 flint glass, he proceeded to enumerate some of the articles which are now 

 being made of crown glass, and which were never before made of glass ; 

 among them were the following :— A glass dairy pan, for setting of cream ; 

 the advanta.'e of using glass, instead of zinc, tin, or lead, is its producing 

 a larger quantity of cream-equal, it is stated, to from 30 to 50 per cent 

 The next articles enumerated were propagating glasses, for horticultural 

 purposes; these supersede the use of metal frames, bee and grape glasses, 

 cucumber tubes and seed protectors, pantiles for roofing, and for domestic 

 purposes, glass pipes, pickle jars, roUmg-pins, pastry pans, jugs, &c. 



The author having also shown the application of crown glass for coloured 

 railway signal lamps, concluded by stating—" I'hat the success which has 

 attended the exertions of the flint glass manufacturers, and enabled them to 

 produce their brilliant specimens, will (he fears) make these humbler sani- 

 ples appear dull and uninteresting, until their cheapness and applicability 

 show in what their advantage consists." 



Altril 21.— Dr. Rogbt, Secretary, V.P., in the Chair. 



" On the Manufacture of Shell Cameos." By Mr. Gray. Six specimens 

 of shells with the cameos cut upon them were exhibited. 



The author commenced by stating that the ancients formed cameos by 

 engraving figures in low relief on different kinds of silicious stones, and 

 generally selected for that purpose those which had layers of different co- 

 lours, so that the figures, or different parts of the same figures, were of 

 divers colours. Such cameos are now made in Southern Europe and m 

 France, where this art has lateiy been attempted to be revived ; but the 

 hardness of the materials require so much labour to be employed m their 

 fabrication, that they are too expensive to come into general use. 



Numerous attempts have been made to substitute various materials, such 

 as porcelain and glass, for the ancient cameos, but their great inferiority has 

 caused them to be neglected. The best, and now most used, substitutes are 

 shells, several kinds of which afford the necessary difference of colour, and 

 are at the same time, soft enough to be worked with ease and hard enough 

 to resist wear. The shells now used are those of the flesh-eating Univalve, 

 which are peculiar as being formed of three layers of calcareous matter, 

 each layer being a perpendicular lamina, placed side by side. The cameo 

 cutter selects those shells which have the three layers composed of different 

 colours, as thev afford him the means of relieving his work ; but the kinds 

 now employed,' and which experience has taught him are the best for his 

 purpose, arc, the Bull's Mouth, the Black Helmet, the Horned Helmet, and 

 the Queen Conch— the two first are the best shells. After detailing the 

 peculiarities of these shells, Mr. Gray proceeded to give an account of the 

 progress of the art, which was confined to Rome for upwards of 40 years, 

 and to Italy within the last 20 years, when an Italian commenced it in Pans, 

 and now about 300 persons are employed in this branch of trade in that 

 city The number of shells used annually, thirty years ago, was about 300, 

 the whole of which were sent from England, the value of each shell in Rome 

 being thirty shillings. To show the increase of this trade, the number of 

 shells used in France last year was nearly as follows :— 



Bull's Mouth, 80,000, at average price each, Is.Sd. .. £6,400 

 Black Helmet, 8,000, „ ^ ^ •• ^'^"^ 



Horned Helmet, 500, „ 2 6.. bO 



Queen Conch, 12,000, „ 1 24 lOO 



100,500 shells £8,960 



The average value of the large cameos made in Paris is about six francs 

 each, giving a sterling value of £32,000, and the value of the small cameos 

 is about £8,000, giving a total value of the cameos produced in Pans, for 

 the last year, of £40,000; while, in England, not more than six persons are 

 employed in this trade. 



The thanks of the meeting were presented to Mr. Gray for his communi- 

 cation, and to Mr. John Turner for two specimens, which he presented to 

 the Society for its museum. 



The second communication was " On a means of rendering Sculptured 

 Sandstone impervious to the effects of our changeable climate and humid 

 atmosphere." By D. R. Hay, Esq., 



The author, after stating the nature and stracture of the various sand- 

 stones, the causes which operate upon them and separate the particles, and 

 the plans usually resorted to for preserving masons' work from the injurious 

 action of the air, said he had found that the ordinary process of saturating 

 the sandstone with linseed oil was ineffectual, and having occasionally used 

 bees-wax as an ingredient in paint, and knowing from experience that it is 

 impervious to the blanching or oxydising influences of the common atmo- 

 sphere, he considered that if applied to sandstone, it would render it very 

 durable. " I believe (observes Mr. Hay,) that it has been used by the an- 

 cients in securing their fresco paintings, by rubbing it upon them, and fa- 

 cilitating its absorption by the application of hot iron, and a similar appli- 

 cation has been recommended in modern times in respect to sculptured 

 marble ; but such a process must be very uncertain as to its efficiency, in as 

 much as the absorption must he very partial and unequal. The plan I would 

 recommend is applicable to statues, vases, and all sculptured architectural 

 decorations— namely, a trough of suitable capacity must be built of brick, 

 with a furnace under it, and the trough filled with sand ; place among the 

 sand, at one end of the trough, a vessel made of tin or copper, and of the 

 requisite capacity, into which put spirits of turpentine or naphtha and bees- 

 wax, in the proportion of two or three pounds of the latter to a gallon of 

 the former, according as the stone to be saturated is more or less porous. 

 Keep the furnace burning until the sand has become sufliciently hot to dis- 

 solve the wax amongst the oleaginous or bituminous spirits iii the tin or 

 copper vessel. Place the stone to be saturated in the unoccupied part of the 

 trough until it becomes of a temperature equal to that which has disso ved 

 the wax, and if the capacity of the vessel admits, let the sculptured stone 

 be immediately removed from the sand and dropped into the adjoining ves- 

 sel when, in a few seconds, it will absorb a sufficient quantity of the wax, 

 held in solution by the spirits, to prevent the humidity of the atmosphere 

 ever acting upon it." 



An interesting discussion took place after the reading of the paper, in 

 which Mr. Ray,"Mr. Tennant, Mr. C. H. Smith, Mr. Crace, and several other 

 scientific gentlemen, took part. 



