1819.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



150 



besides giving a succession of powerful shoclis, possesses an extraordinary 

 power of effecting chemical decomposition: the electro-magnetic machines 

 he had hitherto seen scarcely affording more than a few bubhles of gas when 

 employed in the decomposition of water, while Dr. Wright's machine gives 

 a torrent from the electrodes of the voltameter. Dr. Wright stated that a 

 most powerful machine may be packed in a box 8 inches by 21, which can 

 be carried conveniently in the hand. In medical practice, Dr. Wright found 

 that the slill smaller machine, which he exhibited, is more than sufficiently 

 powerful, though its size is only 3J by I5 inches. 



March 26.— John Cav, Esq., F.R.S.E., President, in the Chair. 

 The following communications were made: — 



"Description of several neiu and simple S/ereoscopes, for exhihiting as 

 Solids, one or more representations of them on a Planed By Sir David 

 Brewster, F.R.S. 



This paper contained the description of a particular stereoscope, con- 

 structed with two semi-lenses, or two quadrants of a lens, united as specta- 

 cles, but in such a manner as to give double images of objects, or of draw, 

 ings of solids, as seen by each eye separately. When two of the images 

 thus produced were united, as in the instrument, the solid, either raised or 

 hollow, from which the drawings were taken, was reproduced. Another 

 stereoscope, called the Total Reflection Stereoscope, was described, which 

 ri quired only one drawing of the solid, the other drawing being created by 

 the instrument and united with the picture seen by the other eye. Single 

 and double reflecting stereoscopes, of great simplicity, and easily constructed, 

 were also descrilied; together v\ith microscopic stereoscopes, which can be 

 carried in the pocket. 



"Description of a Time- Signal for Railways, Steamboats, Sfc." By James 

 S. ToBROP, Esq. 



The present instrument has been devised to meet a great want, which has 

 long been felt, for some certain and effective means of informing or warning 

 the public of the approaching departure of passenger trains. Bells rung 

 within or near the station, cannot answer the purpose, the sound being easily 

 stifled, and apt to be regarded, when loud enough to be heard at any dis- 

 tance, as a nuisance. Clocks are still more useless, as they are visible only 

 at short distances, even when they can be placed on conspicuous positions. 

 This time-signal, or railway trains' monitor, consists of a moveable ball 

 mounted on a lofty pillar, wound up to the top by clock-work, and taking a 

 definite time to descend. For railways this time is set to ten minutes. 

 When the ball is seen at the top of the pole or pillar, passengers approach- 

 ing the station are informed that they have ten minutes; if half-way down, 

 five minutes, and so on. Being capable of being made a conspicuous object, 

 its indications can be distinguished at a considerable distance by intending 

 passengers, who are thereby saved all unnecessary excitement and uncer- 

 tainty in making their way to the station, while the officials are also saved 

 from the annoyance of questioning as to the time the train is due. 



"Notice of a peculiar property of Gutta Percha." By James S. 

 ToaROP, Esq. 



Gutta Percha, when cast and rolled into sheets, assumes a property belong- 

 ing to fibrous substances; it acquires tenacity in a determinate direction. 

 When in the roll or sheet this tenacity is longitudinal, but if a strip be cut 

 from the breadth two peculiarities occur — the strip is susceptible of a definite 

 elongation to nearly five times the original length, and its direction of 

 tenacity is reversed. When it is considered that Gutta Percha is origin- 

 ally a fluid substance, or gum, these peculiarities are curious and remark- 

 able. 



"Description and Drawing of a Rapid Filter, adapted for the perfect Fil- 

 tration of JVater for the supply of Toiims, or for any other purpose where 

 a large quantity of pure water is required." By Messrs. T. and W. Stirling, 

 Bow-Bridge Slate-works, Stratford, Essex. 



The objects and advantages of this apparatus were stated to be — 1st, While 

 it is capable of being so combined as to filter large quantities of water, it 

 also acts upon each gallon that passes, with the same minuteness and deli- 

 cacy as the chemist employs for his most careful operations. 2d, It is made 

 of a material upon which water has no decomposing effect. 3rd, While it 

 may be readily cleansed, it is in no degree liable to get out of order. 4th, 

 It occupies but a small space compared with the quantity of water filtered 

 by it; and 5th, It is so arranged as to be guarded from the disturbing effects 

 of frost or rain, and protected from soot, smuke, and dust. 



A series of slate boxes or cisterns, the size and number of which are regu- 

 lated by the quantity of water required to be filtered, as shown in the draw- 

 ing submitted to the Society, are so placed that the reservoir or pipe from 

 which they are supplied shall have a head of water of about two feet six 

 inches. The water passing along the main-pipe, enters each filter at the 

 bottom through a branch-pipe, and passes through three strata of filtering 

 medium (the lowest of which rests upon a hollow basis, across which a fine 

 wire-gauze is stretched), through which it rises to the top of the filter in a 

 perfectly pure state. The filtered water then passes from the top of each 

 filter through a small pipe into a slate channel, along which it runs into the 

 pipe, reservoir, or other receptacle for the filtered water. The filtering 

 medium consists of three strata of incorrodible mineral substances, and the 

 chamber in which they are placed admits the introduction of a hair-brush 

 such as is used for cleaning bottles, and with this the bottom of the filter- 



bed is readily cleaned of all residium in a few minutes. The apparatus can 

 be adapted to filter any quantity of water from 500 to 50,000,000 gallons, 

 and may be applied not only to domestic use, but to the purposes of paper- 

 makers, brewers, distillers, chemists, bleachers, wool-staplers, printers, and 

 other trades for which large quantities of pure water are indispensable. 

 The usual method of filtering water supplied to towns is by means of reser- 

 voirs of subsidence and filter-beds, which occupy a large space of ground, 

 and at best effect the object very imperfectly. This apparatus, however, can 

 be so managed as to occupy only about one.twentieth part of the space 

 required by the other methods now in use, and may be enclosed in a covered 

 building, so as to protect it from rain, soot, and dust, and, when necessary, 

 warmed by flues to prevent the action of the filters from being impeded 

 during severe frost. 



"Notice on the Ventilation of Pvl/lic BuihJings and Private DveWnys 

 with peculiar reference to the method adopttd by him in the New Police 

 Office, Edijiburgh." By R. Ritchie, Esq., C.E. 



Mr. Ritchie brought under the notice of the Society the method oi' 

 ventilation he had carried into effect at the new police buildings, Edinburgh, 

 which plan was founded upon the principle for which, in 1847, this Society 

 had awarded to him a silver medal and plate, value ten sovereigns. He 

 stated that the certainty of operation of this process and its efficiency had 

 now been fully attested. He described that a furnace, placed at the base- 

 ment of the building, was made to heat, with the utmost simplicity, a very 

 powerful patent hot-nater apparatus, placed 70 feet above it at the roof, for 

 extracting the foul air. The various rooms and cells in the building were 

 each provided with a conduit to carry off the exhaled air, and these conduits 

 terminated in a long gallery under the roof; the extracting apparatus was 

 erected at one part of the gallery at the bottom of an ascending shaft. 

 This shaft terminated in a louvre, so arranged that the orifices of discharge 

 could be regulated (according to the direction of the wind) in the furnace- 

 room at the basement. By means of this powerful appparatus, the exhaled 

 air drawn from the rooms ana cells into the gallery, passed without obstruc- 

 tion into the atmosphere. He pointed out that this plan of ventilation pos- 

 sessed the obvious advantage, that it was free from the risk of the reflux of 

 foul air and vapours of combustion into the rooms and cells, and it is likewise 

 free from danger of fire. Mr. Ritchie stated that this mode of ventilation 

 could easily be adapted for one or for many apartments ; and he considered 

 it applicable to mining ventilation. The consumption of fuel for the ven- 

 tilating apparatus at the police buildings was exceedingly small for the 

 effect produced. He also described .the means provided for supplying fresh 

 air for renovation, which in winter was warmed by means of a mild hot- 

 water apparatus, and the air regulated in moisture in a chamber of prepara- 

 tion. He stated that this method had been applied most successfully by 

 him at various buildings, and referred, amongst others, to St. John's Chapel, 

 Prince's-street, which was equally heated with one fire, which was substi- 

 tuted in place of two stoves formerly used. The success of this plan was 

 attested by the Chairman. He also made some suggestions as to the great 

 advantages which would arise, were systematic arrangements for ventilation 

 incorporated with the construction of buildings generally; and he mentioned 

 various modes for making the conduits for exhaled air. 



THE ARCHITECTURAL EXHIBITION. 



Sir — In the last number of your periodical you have alluded to a drawing 

 which 1 forwarded to the 'Architectural Exhibition,' as appearing again 

 under a change of names. From some cause, probably that of a hasty com- 

 pilation of the catalogue, the drawing was inserted therein as a "Design for 

 a Library," — whereas, there still existed at the back of the frame the original 

 description, and to which the catalogue was revised in the second edition, 

 without nay having named the matter to the parties concerned in its forma- 

 tion. You will therefore perceive that the alteration did not proceed from 

 any intentiou on my part to make one design answer for a different pur- 

 pose. 



I am, &c., 



WVATT PaPWORTH. 



10, Caroline-street, April 20, 1849. 



Drying Closet. — Some recent experiments with a new drying closet at the 

 Middlesex Hospital, show that it is not necessary to have an external air 

 drain. The closet is 6 feet by 8 feet, and 7 feet high, heated by radiation 

 from the flue of an ironing stove which passes through it. The closet was 

 previously tried with an air drain, and it has been found not to be so good as 

 one without a drain. 



6 Blankets. 18 Rugs, 



lb. lb. 



Weight when put in 44 169 



Weight when taken out 23^ 87.4 



Wattr evaporated 20| 81i 



Time in evaporating 1 h. 35 01. 



Temperature of closet when rugs were put in .. 2(10*^ 



Ditto when taken out \W-' 



Fuel consumed equal to one-tuurtb the weight of watt-r evaporated. 



