1848.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL"! 



Hi 



or separate one portion from another, a is the circular metal 

 plate, and h a metiil ring, accurately iitted tofrether ; c, a conical 

 metal plujj forming a core, with a feather d affixed, to form the re- 

 cess for the key to fasten the wheel to the axle. 



Silvering Speculums. — Patented Augusts, I8i7,l)yT.FLKTCHER, 

 of Birmingham. It consists in coating glass, after it is silvered with 

 metal, by the electrotype process, whereby the quicksilver is pro- 

 tected from injury, and a stronger power of reflecting light given to 

 th« si>eculum. The silvered glass plate is lightly and carefully 

 coated on the back, or sihered side, with a varnish composed of tw o 

 ounces of shellac, half a pint of highly-rectified spirits of wine, and 

 half an ounce of the best lamp-black; this varnish protects the quick- 

 silver from damp, and from the acid used in the subsequent process. 

 Before the varnish is quite hard, shake over it from a muslin bag, 

 finely-pulverised plumbago, black oxide of manganese, or any other 

 metallic powder, or cover it with thin metal, sothat the whole surface 

 will be covered with a perfect but thin coat of metal ; after which 

 it is submitted to the electrotyping process, and by this means a 

 thin coating of copper, or other metal, will be precipitated over 

 the entire back of the plate. 



Direct Application of Steam-Power to Mills. — Patented 

 July 29, 1847, by J. Hastie, of Greenock. It consists in the 

 application of direct action of steam-power to turn mills, by 

 making the axis of the crank of the engine serve also for the axis 

 of the mill — whether the same be vertical or horizontal. The 

 shaft is provided with a fly-wheel, which receives an endless belt 

 for driving flour-dressing machines, and on the shaft there is an 

 eccentric for communicating motion to the slide valves. When 

 two pairs of mill-stones are required to be worked by the same 

 engine, it may be effected by causing the piston-rod to pass through 

 both ends of the cylinder, and connecting it at each end with the 

 shafts of the upper mill-stones ; and, in case it should be at any 

 time desirable to work only one of the upper stones, the other may 

 be disconnected. 



WALLER'S PATENT COFFEE-POT. 



This invention consists of a vessel divided into two equal parts 

 by a dished partition A, with the centre depressed and pierced by a 

 hole ; around the edge is attached a bent tube connected with a 

 cock B, forming a passage through the strainer C, from the upper 

 to the lower h:jf of the vessel ; the strainer is finely perforated 



metal. Ascending from within a short space of the bottom of the 

 lower chamber to within nearly .tbe top of the upper one, is a 

 tube E, passing through the centre of the partition and perfora1,ed 

 plate, and which tube is surmounted by a valve D. F is an ordi- 

 nary spout communicating only with the lower division, and fitted 

 with a ground stopper. 



The mode of using the apparatus is this : the stopper being re- 

 jnoved from the spout, the water is poured into the upper half of 



the vessel, the lap is then turned downwards to allow the water 

 to run into the lower half; when it has done running, the ground 

 coffee IS ]iut into the top division, the tap again turned horizontallv. 

 the stopper re-mserted, and the vessel placed on the fire. Wlu^ii 

 the rattling of the valve, and escape of steam from under the lid 

 have continued a few seconds, the cofi"ee-pot is to be taken quite 

 away from tlie fire and allowed to stand about two or three 

 ™-n"*^^',! ■V''!' '*" *''"' turned downwards, when the infusion 

 wiU rapidly filter into the lower division, and be ready for use 

 in a beautifully bright and boiling condition. 



The princi]ile of this apparatus will be readily perceived, 

 \\ hen It IS placed on the fire, the water in the lower division is 

 loi-ced by the pressure of stciim up the central tube, lifting the 

 valve, and made to fall in a uniform stream, ot a gradual/y in- 

 creasmg tempmitnre, upon the coff-ee ; as soon as all the water aliove 

 the inferior orihce of the central tube has been forced up, then 

 on y steam arises ; when the vessel is removed from the fire the 

 valve la Is into its seat, and prevents the re-entrance of air into the 

 lower chamber, after its total expulsion thence by the steam ■ 

 during the period of infusion, the steam in the lower chamber ij 

 allowed to condense, and thus a partial vacuum is ijroduced and 

 preserved for any period, and rendered available for effecting rapid 

 filtration whenever desired, bv the employment of tlie tap. 



From experience we can state that this little apparatus is one of 

 the most useful domestic articles that can be had. It produces the 

 most brilliant and fragrant coffee in three or four minutes. M'e 

 should observe that during the process the vessel is quite closed - 

 consequently, not the slightest quantity of tlie aroma of the cofl-ee 

 IS dissipated. 



ON THE FLOW OF WATER. 



Of the Union and Division of Rmmhig Wafers, u-ith the Lavs (ff 

 their Increase and Diminution. By Bernardino Zendeini, della 

 Citta de Ravenna.— (Translated by E. Cresy, Esq., in his Evi- 

 dence before the Metropolitan Sanitary Commissioners). 



I. A river which unites with another does not cause this latter 

 to rise in proportion to the quantity of water which it brings, as 

 would be the case supposing water to be considered as a solid, but 

 only increases the height by as much as the greater or less velocity 

 of the influent or recipient may permit. On the contrary, if a 

 river in the middle of a canal be diminished by a certain quantity 

 of water, it ought to be lowered proportionally to the velocity of 

 the canal of derivation and the river froni which the water is ab- 

 sti-acted, and such an alteration ought to be perceived not only at 

 the lower part at the point where the water is added or subtracted, 

 but also in the upper. In which law, however, there is much ob- 

 scurity ; what appears certain is, that both in the case of the union 

 and of the separation that the surface continually adapts itself to 

 the alteration in a regular progression, and although the impres- 

 sion arising from such an anomaly does not disturb the whole level 

 of the river if it runs over a long course, it reduces the problem 

 to find the point where the disturbed mixes and unites with the 

 undisturbed surface after following the oscillation of the water, 

 which point in geometric rigour ought to traverse the -whole length 

 to the source of the river, since it would describe a regular curve ; 

 but the course of the water encounters so many impediments and 

 obstructions, that tliese laws do not really obtain. And in every 

 river there is, in fact, a point beyond which the regurgitation does 

 not take place. That, however, as much as possible, we shall treat 

 of in another chapter, when speaking of tie falls of riv^s, of 

 their highest rise and lowest levels. 



For the present it will be sufficient to seek the elevation or de- 

 pression which will be produced in a j-iver by the addition or sub- 

 traction of a quantity of water. 



II. Suppose A B to be the height of a recipient previous to the 

 influx of another stream, let L M be its width in a given section, 

 F G the height of the influent before the union, H I its width. 

 Supposing this latter introduced into the recipient, it ought to 

 experience a certain rise. What will that rise be ? Since the ad- 

 ditional water ought to conform to the width of the section of the 

 recipient, conceive the height F G of the influent altered to that 

 of the recipient A E, then the water of the one will have passed 

 into the other, and since this fresh water presses upon the other, 

 that of the recipient will be obliged to lower its surface, and from 

 the point A will be brought down toC ; likew ise the point E will 

 pass to D and E D = A C, and consequently B D will be the entire 

 height of the recijiient after the addition of the influent waten. 



