1843.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



233 



cover only one fourth of the passage at eafh end of the valve ; and 

 for any other portion between one-sixth and -^ of the stroke, during 

 which it may be thought requisite to introduce the steam as a mini- 

 mum, the plate I, must be made of a sufficient length to cover some 

 intermediate portion of the passage, between one -fourth and one- 

 half. L t , 



Under all circumstances, the distance between the points of the 

 tappets at their nearest approach to each other, should be equal to 

 the length from outside to outside of the two passages that run 

 through the slide valve, and the governor should be so applied as to 

 give to each tappet, a stroke equal to one-fourth of the total stroke 

 of the slide valve. 



Your Glasgow correspondent says that " a slight examination of the 

 drawings mill shorn that though the steam is cut off as soon as the port 

 of the cylinder is half open, admitting steam daring rather less than 

 one-fourth of the stroke;" this is an oversight on his part, and a closer 

 examination of the drawings, imperfect as they are, will convince him 

 (every thing being as shown in the drawings,) that although the steam 

 would be cut off as soon as the port of the cylinder is half open, it 

 would only be admitted into the cylinder during about one-fifteenth of 

 the stroke of the piston, instead of something less than one-fourth. 



It remains for me to thank your correspondent for having called 

 my attention to the error I committed in my former communication, 

 and as I fear that I have already too much trespassed on your valuable 

 space, I shall be happy to answer any questions, or give any informa- 

 tion in my power, if your correspondent will send me his name and 

 address. I was not in England when the Journal for May appeared, or 

 I would have requested the favour of your inserting this in your last 

 number. 



I remain, Sir, 



Your most obedient servant, 



London, June Sth, 1843. H. H. Edwards. 



THE BUDE AND BOCCIUS LIGHTS. 



During the last month two of the Wednesday Evening meetings of 

 the Society of Arts, in the Adelphi, were occupied with the reading 

 of interesting papers describing the Bude and Boccius lamps and 

 their advantages. On the first evening the large room was splendidly 

 lighted from one gas lamp, suspended from the centre of the room, 

 on the Bude principle, when Mr. Bethel read a paper and described 

 its principle. On the following Wednesday the room was lighted in a 

 similar manner with the Boccius light, when a paper describing its 

 advantages was read by Dr. Atkin. We have here given a full 

 description of each light by the respective authors of the papers, and 

 leave it to our readers to judge of their respective merits. They both 

 appear to be deserving of encouragement and the patronage of the 

 public. 



THE Bl'DE LIGHT. 



The Bude light is the invention of Goldsworthy Guruey, Esq., of Bude, in 

 the county of Cornwall, and has been called The Bude Light, a name given 

 to it at the Trinity House, to distinguish it from Mr. Gurney's former inven- 

 tion. Mr. Gurney has, for the last twenty years, been experimenting upon 

 the best means of producing the most powerful and beautiful light. In 

 1822, he invented the light called the Oxy-hydrogen Light, which he fully 

 explained in his lectures delivered in Cornwall in 1822, and published in his 

 book on chemistry in 1823. This light was the result of his experiments 

 with the oxy-liydrogen blow-pipe. The combustion of the two gases, oxygen 

 and hydrogen, issuing from two distinct jets in certain proportions, produce 

 no light, and only a small blue flame, giving off very great heat ; but when 

 a small cylinder of lime is placed behind the jets, the most intense and beau- 

 tiful light is evolved. Some years afterwards Mr. Gurney invented another 

 powerful light, produced by passing a stream of pure oxygen gas through 

 the wick of an oil lamp, whereby a most intense and beautiful light was 

 formed. This light was put up at the Trinity House, where it was seen by 

 Mr. Hume, who was the chairman of the lighthouse committee ; he intro- 

 duced it to the notice of the House of Commons, and it was subsequently 

 adopted for lighting that house. Difficulties occurred in the practical work- 

 ing of this light, and Mr. Gurney determined on still further prosecuting his 

 experiments ; and the result was, the production of what may be called The 

 Atmospheric Bude Light. 



The mechanical principle by which the light is produced, consists of a 

 series of horizontal concentric rings of tubing perforated on the upper part 

 for the escape of the gas placed at definite distances from each other, and 

 so arranged as to regulate the quantity of atmospheric air, and to communi- 

 cate by conduction and radiation sufficient heat to raise the temperature of 

 the gas to a given point, so as to effect the separation of its carbon imme- 

 diately as it leaves the burner, and then by an arrangement above to bring 

 fresh atmospheric air to the proper points of the flame. A perfect lamp wiU 



deposit the carbon in the flame the instant it passes the jet. If so imperfect 

 as to deposit too soon, carbon will be found in the riugs ; if too late, then 

 high up in the flame. There is a point of accuracy required, which practice 

 has determined. This mechanical arrangement brings about a series of che- 

 mical changes involved in the evolution of light and heat, which are very 

 interesting. The rapidity of chemical union governs the respective quantities 

 of beat and light. We may by a too rapid combination produce heat alone, 

 and no light. It has been found by careful measurement, that little or none 

 of the light given off by the inner rings is lost, but that it all passes through 

 the outer rings of flame. By the concentration of a mass of light, a power- 

 ful illuminating effect can be diffused over the whole apartment, and may be 

 softened down by glass shades to any intensity, and tinted, if desired, with 

 any colour. It has been found in the shops in Loudon, where this light has 

 been used, that its effect on coloured articles is very different to other arti- 

 ficial lights, as all colours — particularly blue and green — can be as distinctly 

 seen by it as by daylight. 



Its economy has been proved to be very great. The evidence given by the 

 scientific gentlemen examined before the committee of the House of Com- 

 mons, they proved that for the same quantity of light used in that house, 

 the saving by using the Bude burner is equal to 50 per cent. Professor 

 Wheatstone stated, that the Atmospheric Bude burner he used had 3 con- 

 centric rings, and was supplied with street gas. Its light was equal to 68 

 wax candles, and consumed 20 cubic feet of gas per hour. The Argand gas 

 burner used by him was equal to ten wax caudles, and consumed 5 cubic 

 feet per hour. The Bude Light consumed not quite four times the quantity 

 of gas which the common gas burner did, whilst the light given by it was 

 6i times more intense, thus giving an economical advantage of the Bude 

 Light over the gas light of very nearly double. 



The committee in their report to the House, state that the saving effected 

 upon the lighting of the house by the introduction of this light, was 481/. 9s. 

 per session. The light has given the greatest satisfaction. Its intensity 

 combined with its softness, has delighted all the members of that house. 

 Its effect in the different churches where it has been placed is most excellent. 

 Clapham church is lighted by one burner, which is composed of 5 concentric 

 rings, the diameter of which is 11 inches ; this lights the whole church very 

 beautifully, and so perfectly, that the congregation is able to read in the 

 shadow near the pillars supporting the galleries. In Christ church, Albany- 

 street, a more perfect illumination has been produced by two burners than 

 by the 72 Argand burners previously used there. But one of the most im- 

 portant advantages of this light is, that it proves a most perfect ventilator. 

 It is always fixed high up in the room with a large escape pipe over it lead- 

 ing to the chimney, or externally entering, which carries off all the products 

 of the combustion of the gas ; without this pipe it is not considered that 

 Loudon gas can be pleasantly burnt. 



THE BOCCIUS LIGHT. 



The burner of the Boccius Light consists of one or several concentric 

 rings ; when more than one is employed, the inner ones rise to a higher 

 level than the outer, as shown in the annexed engraving, B B, and are 

 perforated with numerous minute holes, in about the proportion of 60 to a 

 circle of an inch in diameter. The inner are supplied with gas from the 

 outer, and to make up for the diminished supply, the holes in the inner are 

 rather larger. Above the burner at a given distance, two concentric metallic 

 chimnies (D), are placed, whose diameter is regulated, in great measure, by 

 that of the outer ring. The chimneys are supported by three wires (C), upon 

 the glass holders, and surrounding the whole, a glass funnel (F), proceeding 

 from the level of the burners to the top of the metallic chimneys. The glass 

 in the smaller burners is perfectly straight ; in the larger ones, slightly bell 

 shaped at the bottom. When the gas is turned on and lighted, the lower 

 part of the burner — that is, the rings (BB), and crutch (A), become to 

 some extent heated, and communicate a portion of their heat to the ascend- 

 ing gas ; the amount of heat is from the construction (accuracy having been 

 attained by experience) so nicely adjusted, that no carbon is deposited in 

 the ring ; but the warm gas escapes, ready to deposit its solid matter o.i a 

 slight increase of temperature. The cold air, too, hi rushing between the 

 crutches and rings becomes warmed, and the burner is thus supplied with 

 hot air, no air being admitted except from the bottom ; it, of coune, can 

 produce but a very insignificant cooling effect on the flame. The chimnies, 

 especially the inner one, robs the ascending current of a great portion of its 

 heat, which it in turn communicates to the upper part of the flame, and 

 carries the particles of carbon there to an intense temperature, and causes 

 them ultimately to unite with oxygen. The quantity of air entering is so 

 regulated by the size of the separate openings, that it produces -.early a per- 

 fectly cylindrical, instead of a conical flame. From some cause or other, the 

 reason of which the inventor is unable satisfactorily to explain, the pro- 

 ducts of combustion are separated from one another, and appear at I I 

 positions. The ascending current of air between the glass and outer chimney 

 supports combustion, as of a taper ; when placed between the two chimnies 

 the taper is extinguished, and re-lighted again when brought over the centra! 

 aperture. The novelties in arrangement of this lamp are the rising concen- 

 tric rings and the metallic chimnies. We have in the engraving represented 

 a large double ring burner in the centre ; the diameter of the outer ring is 

 5 inches ; and of the inner, 3 inches. This size burner will consume about 

 55 feet per hour, and be equal to 22 Argand burners, consuming 5 feet per 



