1848.J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



ISS 



then alluded to the value of these different kinds of coal for affording gas, 

 and ronsequently for affording light by tlie combustion of their gases. In 

 ascertaining this, the quantity of gas given off from tlie coals is taken into 

 account, along with the value of tlie gases themselves for affording liglit. In 

 this way he has fixed the value of the coals as follows : — English caking coal 

 being 1 ; that of the English parrot coal is on an average 23 ; and that of 

 the mixture of Scottish parrot coal, as used in different towns, as 6. 



In the second part of the paper. Dr. Fyfe alludeil to the methods of finding 

 the value of coal gas, for the purpose ol illuminalion, and more particularly 

 to a new mode of determining the durability ; in other words, the time re- 

 quired for consuming a certain volume of gas, and consequently the con- 

 sumpt in given times, and by means of which, also, the specific gravity of the 

 gas could be ascertained. From numerous experiments which he had per- 

 formed, he had come to the conclusion, that when coal gases are burned 

 from the same burner, with the same height of flame, the consumpt is as 

 the square roots of tlie pressure necessary to keep up the combustion, at the 

 length of flame fixed on ; and that, consequently, the time required for the 

 consumpt of equal volumes is inversely as the square roots of the pressure 

 He had also come to the conclusion, that the durability, in other words the 

 time required for the consumpt, depends on the specific gravity, and that the 

 same law is applicable ; consequently, the specific gravity being known, the 

 consumpt can be determined; as the consumpt being determined, by the 

 pressure, the specilic gravity can be ascertained, the rule being, the specific 

 gravity is inversely as the square roots of the pressures, necessary to keep 

 the gases burning, from sindlar burners, at the same height of flame. Dr. 

 Fyfe stated, that he had put these different rules to the test of experiment, 

 with gases which he had prepared from different coals, and also with the 

 gases found in different towns, and he exhibited numerous tables, showing 

 the very close correspondence between the results obtained experimentally, 

 and by calculation. He then exhibited an instrument by which the dura- 

 bility and specific gravity, could by the rates stated, be determined. It con- 

 sists of a jet burner, of the -lOth of an inch in diameter, to which is adapted 

 a scale for measuring the height of flame, and a pressure gauge for ascer- 

 taining the pressure under which the gas is burning, at the length of flame 

 fixed on. In this pressure gauge is fitted a graduated scale, with a burner, 

 by which the pressure can be read off, to xio'h o' s" iacii. Along with 

 this a table was given, showing the consumpt of gases in a given time — the 

 time required for tlie consuiopt of equal (luantities, and the specific gravities, 

 according to the pressures indicated by the gauge. In the table the pres- 

 sures ranged from -nniths to -fSijths of an inch, which embraces all the pres- 

 sures likely to occur with the jet burner stated. 



Dr Fyfe, in conclusion, alluded to a photometer, which, so far as he was 

 aware, is not noticed in any publication, and which, he believed, was the 

 invention of Professor Bunsen. It consists of a paper screen besmeared 

 with a solution of spermaceti in oil of naphtha, excepting at a part around 

 the centre. A candle placed behind this transmits light in such way as to 

 make the part uncovered easily observed, but when another light is placed in 

 front of the screen, at a certain distance, according to the intensity of the 

 light the spot disappears, and the paper becomes uniformly of the same ap- 

 pearance. In using other lights, the distance at which the uniformity on 

 the surface of the screen is occasioned, depends on the intensity of the light; 

 and thus, according to the usual law, the illuminating power of different 

 lights is determined by the square of the distances at wliicli they are situated 

 from the screen. Dr. Fyfe stated that he had put this method to the test of 

 experiment, and found it extremely accurate, and much more easily managed 

 than the shadow test. He exhibited the screen in connection with the pres- 

 sure gauge burners, already described, by tlie use of which, the illuminating 

 power, the durability, and the specific gravity of coal gases are very easily 

 and quickly determined ; and hence the value of an instrument of this kind 

 to those travelling from place to place, with the view of ascertaining the 

 value of coal gas in different towns ; and of ascertaining the value of dif- 

 ferent kinds of coal for affording gas, and consequently for affording light by 

 the combustion of their gases. 



2. ** On the Composite Ellipse, as an element in the useful and ornamental 

 arts, — being the second of a series of short papers upon the Harmony of 

 Form." By Mr. D. R. Hay. 



Mr. Hay said that the paper and illustrations be now brought before the 

 Society would show that the composite ellipse, as he described and arranged 

 it, was an important element in the useful and ornamental arts. He then 

 explained the relation which his composite ellipse bore to the circle, and to 

 the regular ellipse; also his mode of descrihiiig it, with an analysis of its 

 composition. For this purpose he exhibited six large diagrams. He then 

 went on to show that its beauty consisted in the variety of its parts being in 

 an equal ratio to their uniformity ; and that it was to regulate and classify 

 the various developments of this variety, that he iiad in his work on " First 

 Principles of Symmetrical Beauty," classified a series of forty-two of those 

 figures, by an application of the laws of numerical ratio. 



Mr. Hay then stated that he had brought the same subject before the 

 Society about three years ago, as calculated to improve the practice of 

 various arts ; and that as it bore upon the humblest productions of the 

 potter's art, the mechanic and the cottager might have, without additional 

 cost, household utensils of forms as beautiful as the finest specimens of the 

 hantique. 



Mr. Hay then observed that it had lately been stated in the Society that 

 his composite ellipse had not novelty to recommend it, but had long been 



familiar to every one who had given any attention to the subject; and that 

 Nicholson's " Dictionary of Architecture" had been referred to in corrobora- 

 tion of this statement. Mr. Hay, however, stated that neither the composite 

 ellipse, his method of describing it, nor its application to the drawing of 

 vases, was pulilisbed in Nicholson's " Dictionary of Arcbilccture,"orelsewhere, 

 before he exhibited them to the Society, as just stated. 



3. " Description of a new Ball Stop-coci for Water Cisterns, and of a 

 Nase-coci for Cas/ts or Vats." By Mr. Daniel Erskine. 



The new ball-cock consists of two flat surfaces ground air-tighl, having 

 port holes for the water when in certain positions, and furnished with a 

 spiral spring, that keeps the surfaces in contact. This spring is screwed 

 down to the pressure of the water tliat it is fitted for, and as the water tends 

 to lift it off the face, this gives it slight friction on either side, and it is not 

 so liable to get fixed as the present ball-cocks are. The same kind will be 

 of great advantage for gas-works, distilleries, and breweries, where large 

 nose-cocks are required, and will be much less expensive. 



4. " Description of a Model of a Stop-coci for Corrosive Fluids." By 

 Mr. James Robb. 



This stop-cock is intended to obviate the tendency to stick fast, which 

 the plugs of all the common kind have, especially when the fluids are of a 

 corrosive or drying nature, such as common gas ; aoil as it will have no 

 tendency to leak, it may be employed with advantage in oil, beer, or water 

 casks. Its principal peculiarity consists in using vulcanised india-rubber 

 tubing, connected with the pipe by screw couplings, and compressed by 

 means of a screw, or otherwise, to any extent required, by which the flow of 

 gas, or other fluid, may be regulated at pleasure. 



INSTITUTION OF CIVIL ENGINEERS. 



.■ipril 11.* — Joshua Field, Esq., President, in the Chair. 



The paper read was the second part of a communication made in the year 

 1841, descriptive of the " Bann Reservoirs, County Down, Ireland." By 

 I. F. Batemav, M.I.C.E. 



The first part, of which a short abstract was read, gave the object of the 

 construction of these reservoirs, which were undertaken with the view of 

 regulating the quantity of water in the River Bann, and more effectually 

 supplying water-power to the flourishing and increasing establishments on 

 its banks ; this river is, from the bare and naked character of the Mourne 

 mountains, among which it rises, naturally liable to the greatest irregularity 

 in its volume ; devastating floods frequently pour down the channel, where, 

 a few hours previously, there was not sufficient water for agricultural pur- 

 poses. Greatly injurious as this must have been to the agriculturist, it was 

 irifinitely more so to the mill-owners, who depended entirely on water-power 

 for tJieir manufactories. Mr. Fairbairn was consulted on the subject ; he 

 examined the locality, and advised the formation of reservoirs ; the author 

 was then appointed the engineer, and, acting in some degree upon the sug. 

 gestions of his predecessor, whom he continued to consult, the worUs were 

 undertaken which are described in the present paper. The peculiarities in 

 the .\ct of Parliament, granted in 1836, constituting the proprietors of the 

 mills a joint-stock company, for the formation of the Bann reservoirs, are 

 detailed. Th,; works vveie originally intended to have been more extensive 

 than have been really executed. The reservoir at Lough Island Heavy is 

 alone described; the ground in that spot was admirably adapted for that 

 work, being the bottom of a basin, which was bounded on all sides by rugged 

 hills of granite ; in the centre of the basin was a small lake, at the bottom 

 of which was discovered a bed, several feet in thickness, of fossil confervce, 

 similar to those discovered by Professor Silliman, at Massachusetts, North 

 America. This interesting geological fact was first noticed by Dr. Hunter, 

 of Bryansford ; the conferva; appeared like an impalpable powder, but whea 

 viewed through a powerful microscope, they were found to be regular 

 parallelograms, many of them covered with stria;. They are described by 

 naturalists as the fossil skeletons of minute vegetables. The situation fixed 

 upon for the reservoir rendered necessary the construction of four embank- 

 ments, between the hills, so as to raise the water to a height of 35 feet above 

 the summer level of the lake. The particulars are also given of a series of 

 observations with rain gauges, continued for two years, for the purpose of 

 furnishing data for computing the extent of reservoir which would be necessary 

 to insure a supply of water throughout the year. The continuation described 

 the subsequent works, which consisted of the Corbet Lough reservoir, which 

 was designed as aa auxiliary pond, to receive the flood-waters of the lower part 

 of the river, and to retain the night water, to be discharged again during the 

 day, immediately above the more extensive mills on the river. A water- 

 course, of considerable dimensions, was constructed to effect this, and aa 

 embankment was thrown across the narrow outlet of the lake, the water 

 being admitted through self-acting flood-gates, which closed as soon as the 

 lowering of the river created a current in the contrary direction. The details 

 of the construction of all these works were given ; and it was shown, by 

 calculations based upon actual experiment, and observation of the quantity 

 of water received, stored, and delivered from the reservoirs, that their con- 

 struction had increased the value of the mill-power of the River Bann full five- 



* This paper was accidentally oraitted in the report of laat month's proceedings, 



25 



