May 2'J, 1865.] 



* KNOWLEDGE ♦ 



459 



not by any meaus contined to structural work. The details 

 of properly apportioned houses are shown in many cases to 

 be workable in zinc. 



There is a very large display of artificial stone, marble, 

 «tc., but one of the hits of the exhibition is the show made 

 by Messrs. Lindsay it Co. of tire-proof columns. The 

 principle is a core of cast-steel, enveloped in a decent look- 

 ing casing of concrete. This system has, we hoar inde- 

 pendently, already proved all that could be desired, and 

 modidcations are appliable to an almost endless varietj' of 

 purposes. A model is shown of a bridge built and railed 

 on this principle. 



The proposed Manchester Ship Canal, and the periodi- 

 cally filthy state of the Thames envelop with unusual 

 interest anything which promises to be of use in eft'ectually 

 controlling the dow of water, and the maintenance of the 

 river-bed. ilessrs. Wiswall it Collier exhibit a well-made 

 model, on a scale of half-inch to the foot, of their Tilting 

 Weir, as introduced for the improvement of the Mersey and 

 Irwell navigation, and for the prevention of fioods. A 

 number of gates or panels are held in a tilted position in a 

 way similar to what we should see were a number of boards 

 rested against a table. Their line of suspension is below 

 the centre of the gate.s, so that the up])er portion is the 

 heavier. The lower edge of each gate has attached to it a 

 chain which, at its other extremity, is connected to a lever 

 on the bank of the river. The bottom of the gates being 

 toward the stream, the water collects until it tops the weir. 

 Sir Frederick Bramwell, when before the Committee on the 

 ^lanchester Ship Canal, said of the system that it appeared 

 to him to be the very best system of opening weirs that he 

 had seen. It had a great advantage in being readily worked 

 by hand. In pointing out some of the merits possessed by 

 the weir he said that the upper part of the panel being 

 greater that the lower, when the water is only just topping 

 the weir, the percentage of the extra pressure upon the 

 bottom is obviously greater than the pressure upon the top 

 but when the water rises the percentage of the pressure 

 upon the bottom is diminished, and then the weir is 

 capable of tilting. When there is no flood going on it 

 is perfectly competent for the man in charge to open in 

 succession one or two of these panels or gates, and allow 

 the water to flow under rather than over, so that even in 

 the absence of flood the current can be directed periodi- 

 cally across the whole width of the river, and along its 

 bottom thereby keeping it clean. The river fitted with 

 such a weir would be in as good condition as if there were 

 no weir at all. 



One of these weirs has been fitted at Throstlenest, and 

 Mr. Hopkinson, Mayor of Manchester in lt<S2-3, said that 

 it answered admirably under the test of two recent floods. 

 The navigating depth of water had been improved, and 

 the weir was now no obstruction iu time of flood. 



Close to this exiibit is a model of Mr. A. Dowson's 

 system of open groynes for protecting foreshores. They 

 consist of a framework of iron or other rods, and claim 

 as their advantages their open construction, which, while 

 arresting or trapping the shingle, allows the water to pass 

 freely through the openings, and so preventing the back- 

 wash which generally renders solid groynes less eflicient 

 than coidd be desired. They are in use at Brighton, and 

 at St Anne's, near Blackpool. 



A number of other models of a more or less interesting 

 character are to be seen, including one of the Newhaven 

 Harbour Breakwater, and another illustrating one pavilion 

 of a projected military hospital for a hot climate, by 

 Major-General Sir Andrew Clarke, E..H, and Mr. E. 

 Ingress Bell. 



Sailors and those who go down to the sea in ships will be 



pleased to see the advance that has been made in con- 

 densers for producing fresh-water. Spticinu'us of con 

 donsors for diU'eront kinds of vessels, from a yacht up- 

 wards, are shown. Tiic apparatus necessary for a yaclit- 

 launch or torpedo-boat will make fifty gallons of pure fresh 

 water per day of twenty-four, on a low consiiuiption of 

 fuel. This quantity of water is sullicient ti> supply fifty 

 men. The space occupied by the whole apparatus is small. 

 The boiler is made of copper, with seven water-heating 

 tubes in combustion chamber, and the whole can be taken 

 to pieces for cleansing purposes by unskilled laliour. The 

 condenser can also be cleansed in place by simply blowing 

 through with steam from boiler. The water is sup- 

 idied to boiler by an " injector," or, that failing, the 

 liaud-pump can bo applied. The condenser passes the 

 fresh water into the receiving-tank without a pump, 

 through a filter in the top of tank, and aerated ready for 

 use. The total weight is approximately 300 lb. 



There are several domestic .ippliances exhibited of greater 

 or less utility, such as sash-l'asteners, terracotta articles, 

 wood-flooring, ic, one of the most striking being the 

 exhibit of decorated enamelled iron. To some of these we 

 may have occasion to refer later on. 



In perusing the catalogue, however, one is apt to bo 

 startled by reading the following description of an exhibit : 

 " Improved combined safeguard and rail-cleaner (or tram- 

 ways. The apparatus is apjilicable to engines and cars 

 alike. The safeguard removes any ]ierson fallen on the 

 ground without any injury, and prevents in all cases neither 

 the person nor any part of the body, as legs, or arms, or 

 hands, to come into contact with the wheel and being 

 crushed or otherwise injured, even in cases of children of 

 any age. The ajiparatus is lowered and lifted either 

 directly or automatically. The rail-cleaner fixed to engine 

 or car keeps the groove clean, can be set to work or be 

 lifted out of the groove according to the requirements of 

 the service, and thus reduces the tractive power required of 

 horses to one-sixth of its normal conditions." 



The number of visitors to the Exhibition last werk was 

 87,-lGO, making, during the fir.st three weeks it was open, 

 280,009. On Monday there were 73,G3t — a greater number 

 than was recorded on any one day during the time the 

 Fisheries and Health Exhibitions were opc^n. 



TRICYCLES IN 1885. 



By John Browning. 



(^Chairman of the London Tricycle Clul.) 

 MAPS FOR TRICYCLISTS. 



NEARLY all travellers delight in maps, and even pass 

 hours pleasantly in poring over them. To tricyclists 

 maps are indispensable. Route-cards are no doubt valuable, 

 but, should circumstances render some departure from the 

 intended route necessary, a map must be resorted to. 



The best maps published in England are those of the 

 Ordnance Survey. These are from data taken by the Royal 

 Engineers, and they are sold at the offices of the Ordnance 

 Survey in St. Martin's-lane, W.C. Those drawn to a scale 

 of one inch to a mile are the only kind adapted to the use 

 of tricyclists. They are issued in sheets IS in. long by 

 12 in. high, including country eighteen miles by twelve, 

 and are published at one shilling each sheet. As elevations 

 are very fully and accurately shown on them, the relative 

 advantages and disadvantages of diff'erent routes can readily 

 be determined ; they are therefore admirably adapted for 

 consultation when planning a journey. But lieing printed 



