1842.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



321 



sewer with a hinged door half its height, fitting with a water-tight joint : it 

 is opened and closed by means of a jointed rod, which is worked from the 

 level of the street. A liead of water is allowed to collect against the closed 

 door until it is sufficiently heavj-, when the door being suddenly opened, the 

 whole mass of deposit is carried forward by the rush of water. The opera- 

 tion is repeated with a head of 3 ft. of water at intervals of half a mile, 

 until the whole of the accumulation issues at the outfall, thoroughly cleansing 

 the sewer. After this arrangement of apparatus had been some time in use, 

 an improved form with a side entrance, as shown in Fig. 2 was contrived, 

 and is now generally adopted in situations which admit of it. 



By this simplified arrangement the stop-gate can be worked without the 

 mechanical contrivances of the other method, and an easy access is afforded 

 to the sewers. This latter mode is generally adopted, and the success of the 

 plan is stated to be perfect. 



All the details of the construction of the stop-gates and the sewers, as 

 well as of several improvements in the building of the gully-holes and col- 

 lateral sewers, are given, with the result of the velocities of the currents of 

 water from heads of various heights. Drawings of all the several kinds of 

 apparatus invented by the author were presented, and tlie models which 

 were exhibited were explained by Mr. IJurton, the manufacturer of the 

 flushing apparatus. 



Indicators for Steam Engines. 

 Mr. Farey exhibited and described one of a set of indicators for steam 

 engines, made by Mr. Penn of Greenwich, for the French Government, to be 

 used in trying experiments on the steam vessels in their navy. The con- 

 struction was the same as those made by Mr. M'Naught of Glasgow ; but 

 the instruments were larger and better proportioned. Mr. Farey availed 

 himself of the opportunity of describing the construction, the operation of, 

 and the quaUties required in a good indicator, and then exhibited a series of 

 indicator cards, either taken by himself or by friends whose accuracy could 

 be depended upon. They extended from the year 1817 at short intervals 

 down to the present time, and showed a great improvement in the applica- 

 tion of steam in engines : in fact, Mr. Farey was of opinion that the origin 

 and progress of the modern improvements in engines might be traced by a 

 series of cards carefully taken at various periods, and he promised to 

 contribute a more extended communication on the subject during the 

 ensuing session. 



ROYAL INSTITUTE OF BRITISH ARCHITECTS. 

 July 11. 



A paper was read giving a •' Description of the Roof suspended over the 

 Panorama in the Champs Elysees, Paris," by M. Hittorff. 



The Hon. Secretary, Mr. Bailey, observed, that although the Germans 

 attribute the invention of panoramas to Prof. Breisig, of Dantzic, it is gene- 

 rally admitted that they are of English origin, and that the first was exhibited 

 in 1793, by Robert Barker, in the city of Edinburgh. The most important 

 building for such exhibitions, one far surpassing any at that time existing in 

 foreign countries, was erected in London by Mr. T. Horner, and is known as 

 the Colosseum, Regent's Park. The plan is a polygon of sixteen compart- 

 ments, whose interior diameter measures about 1234 ft. The dome is con- 

 structed of timber, curved and arranged upon the principle of Phillibert de 

 Lorme, and is covered with copper. In the centre of the building are two 

 concentrical cylinders supporting three galleries, as well as supporting the 

 centre of the dome or roof. The rotunda since erected in Paris surpasses in 

 magnitude even this vast edifice. Among the various designs for embellish- 

 ing the Champs Elysees, M. Langbois suggested the idea of a rotunda for 

 the exhibition of panoramas. The ground was granted to him for a term 

 of 40 years by the Municipal Council on the following conditions : — 



1. The diameter of rotunda to be 130 ft. 



2. The roof to be conical, and without a central kingpost. 



3. The rotunda to be lighted by a cycle of glazed sashes. 



4. The intervention of any obstruction between the sashes and the wall of 

 the rotunda (thereby casting a shadow upon the canvas) to be carefully 

 avoided. 



5. And finally, all these data to be severally complied with at the least 

 possible expenditure. 



Considering the difliculty of constructing a building of such dimensions 

 without a central kingpost, and the great expense of arched timberwork, 

 together with the solid structure of the walls indispensably requisite to resist 

 the thrust of the wooden vault, the artist resolved to apply (in the construc- 

 tion of the new building) the principle of suspension adopted for bridges, by 

 means of chain cables. The site of the rotunda not allowing of the adoption 

 of stays fastened at a distance from the building, it was necessary so to con- 

 trive the buttresses that they should hold the cables and resist their tension. 

 Their number, amounting to 12, gives a subdivision of the wall of the rotunda 

 into arcs ; and it may be considered, at the level of the stone cornice, as a 

 polygon, whose sides adjacent to one and the same buttresses ofiFered a two- 

 fold force opposed to the strain of the cables. In this way the resistance 

 was obtained nearly at the expense of the cornice and the wall ; and by 

 adopting] two circles vrith the cables passing between these circles, ,the 



upholding chains can be strained as required. These cables pass at an angle 

 upwards, over vertical rods, which rest on pivots on the inner edge of the 

 cornice wall, which is about SJ ft. in thickness; they then rest on the outer 

 edge of the cornice wall, and the ends of the cables are carried to the abut- 

 ment walls and are there fastened. The building was commenced in October 

 1838, and covered in January 1832. It attains a mean height of nearly 

 50 ft., occupying a surface of nearly 21,653 square ft., and its circumference 

 is composed of a mass of building above 16 ft. in depth, having three stories 

 distributed into apartments over a space of 520 ft, ; and the cost of the 

 whole was about £13,000. 



Mr. T. H. Wyatt directed attention to Forster's Patent Stoneware slabs 

 for preventing damp rising in walls. He had found from experience, that 

 slate was not only porous, but too brittle for the purpose, particularly where 

 bouses or buildings are likely to settle ; whereas this material is not only 

 impervious to wet, but can be made to any thickness, and sufficiently strong 

 to resist the greatest pressure. 



ON LIGHTNING CONDUCTORS. 



Sir — Having erected several lightning conductors on Mr. John 

 Murray's principle, a description of them may not be an uninteresting 

 subject for your Journal. 



The head is a copper gilt point, 2 ft. long, lA inch diameter 

 in the thieki st part, screwea into a \ in. bore copper gas tube, 

 which is perforated just below the insertion of the head (" to 

 allow the electric matter to act upon the external and internal 

 surfaces," as Mr. Murray directs in his Essay on Aerial Elec- 

 tricity), and must be continued in as straight a line as possible 

 to the foundation of the building, where it must terminate in a 

 trough filled with water. 



The first erected by me was at Kirkstal church, near Leeds, 

 the spire having been struck by lightning on the 29th April, 

 1833; the finial and stones of the upper part were secured by a 

 wrought iron bar formed as at A, terminating at 5 feet below 

 the finial, a 4-inch flange being sunk into the finial and bedded 

 upon the top stone of the spire; at the bottom of the iron bar 

 was a washer, screw and nut, to tighten the shaft joints, and 

 add to the security against high winds by the increased weight 

 of the mass; the finial was fixed on to the bar with Roman 

 cement. From this nut to the bell was a space of 40 feet, with 

 no intermediate metal except the chain bar of iron at the base 

 of the spire on the line of the cornice. The fluid passed 

 through the north belfry window in a north-easterly direction, 

 leaving the chain bar and the bell oninjured, but the north-east 

 face of the octagon spire was burst asunder, the north-east 

 pinnacle and part of the buttress destroyed, as also the north 

 lucarne of the spire, and the buttress shaft cut obliquely towards 

 the lead flashing of the roof of the body, 

 which was torn up, and the north west 

 pinnacle thrown from the buttress shaft, 

 all the corner stones disturbed, and the 

 slates broken by the stones of the tower 

 and spire, and considerable damage was 

 done inside the building ; the finial A and 

 the lower stone B were so shattered that 

 had not the molding of A been different 

 to any other, I should not have discovered 

 that it had been a portion of it; this was 

 found 80 yards from the building, and the 

 fragment did not contain 3 cubic inches; 

 the stone was 2 ft. 9 in. high, and 2 ft. 3 

 in. diameter ; the lead appears to have 

 attracted the electric fluid on its explo- 

 sion in the spire, yet that on the south 

 side escaped injury altogether. When 

 the spire was rebuilt, a cupper gilt cross 

 was placed on the point of if, the lightning rod extending 2 feet above 

 and attached to it, a continuous line of tube formed by 9 feet lengths, 

 screwed together with couplings, which rests upon holdfasts of iron 

 wrapped with old silk dipped in melted tallow; this plan of coupling 

 is bad, as no allowance is made for the expansion of the metal, and 

 consequently during the third summer one of the joints close under the 

 belfry window broke, but as the lower part of the rod h^is not left 

 the upper more than 2 inches, I believe it to be of little consequence 

 as the stream would be alnwai continuous ; this rod terminates under 

 ground in a stone trough about 2 ft. (1 in. deep, and 18 inches square, 

 which forms part of the line of drains round the church, made to con- 

 vey the rain water from the spouts, and so placed below the drains 

 that it must be always full. I have since this attached one to the 



