1850.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



331 



the shaft, as before, carryins the plates or projections ; a' shows a de- 

 I iched purliou uf uue of these plates, io which the curved part a^ to a^ is 

 brought fiirivard and armed wiih a steel blade, aiisweriug the purpose of 

 the separate coulter /i' in fig. 1; e is the mould-board, and y' the share, 

 as before. Fig 3 is a form of plough suiiable lo the tillage of greeu 

 crops ; a' is a portion of the plate or projection, seen edge\va)s ; e' and e' 

 are r ghl and left mould-boards, and t/' a plain spenr shaped share. The 

 number of plates or projeclions, and also the number of ploughs in each, 

 m.ij be laricd. 



On a Gas Stove. By Mi. W. S. Ward. 



WM 



Fig. 1. i-if. -. 



The novelty of the stove consists in constructiiiir it of iron 

 plates in a vertical position, so as to expose considerable surfaces 

 for the absorption of heat from jets of gas, and for the radiation 

 of the heat. The author found that his apparatus was sufficient to 

 raise the temperature of a moderate sized room from 5° to 10° 

 Fahrenheit, with a consumption of about three feet of gas per 

 hour, costing about 2(/. for ten hours; and that it was particularly 

 useful in warming a bed-room, where only a slight elevation of the 

 temperature was required, and free from the production of dirt or 

 smell. 



The annexed engraving, fig. 1, is a front view of one of the 

 stoves, and fig. 2 a vertical section; it consists first of a sheet of 

 plate-iron to fill up the usual opening of a fire-place, w ith a hole 

 through for a chimney, and two other plates of iron placed about 

 three inches apart, and inclosed round the rim ; near the bottom 

 are perforations to admit air, and a small door with a burner, con- 

 sisting of several small jets inside; when the gas is lighted, it 

 heats the air inside, and the surface of the two iron plates; by 

 this arrangement all unpleasant effluvia is conveyed away througii 

 an iron pipe that is made near the top, and which leads into the 

 chimnev of the room. 



Mr. McPherson explained an Appnratus for frev 

 pipes birrating by Frost. The apparatus is shown in 

 the annexed figure,and is acted upon by the expan- 

 siim of water, just as it is on the point of freezing. 

 Let A represent the supply pipe; B a double-action 

 valve; C the waste-pipe; F a copper tube contain- 

 ing the liquid to be frozen; D, the bracket to sup- 

 port it to an iron plate. Now, if frost acts on the 

 copper tube F, it will expand the water therein, 

 elevate the piston E, and push up the valve B, 

 from its seat, and thereby open a communication 

 with the naste-pipe C, through which the stand- 

 ing water in tlie Jiipe A, escapes, and finally 

 shuts against the supply pipe A, tints accomplish- 

 ing the shutting off the water and emptying the 

 pipes. 



A new Method of Supporting the Speculum of Large 

 Telescopes. By Mr. Lassell, of Liverpool. 



Mr. Lassell explained by a diagram the method 

 he proposed to construct the speculum of large 

 reflecting telescopes to prevent any sensible flex- 

 ure. This he proposes to do by casting on the 

 back of the speculum several ribs, and placing an 

 additional plate behind with several perforations, 

 each having a pin or lever supported on centres, 



■enting Water- 



when the speculum is placed in a horizontal or inclining position. 

 It is supported by these pins or levers acting against the ledges 

 of the ribs; for a 2-feet speculum he proposes to cast five ribs 

 at the back, and have about eighteen pins or levers to support it. 



Mr. Buchanan e.xplained a new kind of Valve for Waterworks. 

 It consists of a flexible web made of India rubber strained over a 

 metallic surface, having one or more hollow grooves, or a hollow 

 space. AV'hen there is the slightest pressure on the top of the 

 valve, the flexible web completely seals the aperture over which it 

 is placed. The annexed engravings show two examples of Mr. 

 Buchanan's invention fig. 1; A is a valve with a plate having two 

 grooves covered with a web h of india-rubber; c is a dead plate 



'd) ^ 



Fi?. 1. FiK 2, 



with a raised rim fixed in the orifice, and d is the orifice of a pipe 

 with a knife-like edge. When the valve A is pressed down, the web 

 where the grooves are. is gently pressed against the two edges of 

 the plate e and orifice d. and closes the aperture. Fig. 2 is 

 another form ; the valve A has a hollow plate covered with the 

 web, which, when pressed against the edges surrounding the aper- 

 ture c, completely closes the opening. 



On a new and ready Process for the Quantitative Determination of Iron. 

 By Pr. F. Filnnv. 



The author recommends the emplovraent of the cbromate and bichromate 

 of potash for the estimation of iron in the common ores of the metal, and 

 especially for the analyses of the clay-band and black band ironstone of this 

 country.' He was led to the application of those salts in the course of some 

 investigations on the materials and products of the manufacture of alum from 

 " alumtshale," in which he was much retarded by the want of a ready 

 method for estimating the oxides of iron. The chromates of potash give 

 very exact results, and possess the great advantage that a much larger 

 quantity of material may be operated on than can be conveniently trdted 

 by the usual methods. For practical purposes, he says, the bichromate is to 

 be preferred. The process requires no other apparatus than that commonly 

 used for centigrade testing, which is familiar to all persons engaged in 

 chemical pursuits. It may he easily and rapidly executed, occupying only a 

 fraction of the time required for the process of estimating iron by precipili- 

 lion as the sesquioxide ; and it is not interfered with by the presence of 

 alum and phosphates which usually exists in the ore. The method is based on 

 the well-known reciprocal action of chromic acid and protoxide of iron, 

 whereby a transference of oxygen takes place, the protoxide of iron beconiiiig 

 converted into sesquioxide, and the chromic acid into sesq'iioxide of chro- 

 tuium. 



A Notice of very powerfid Magnets made by the process of M. Elms 

 and under his direction, by M. Logemon, Optician, Haertem. By Sir L). 

 Brewster. 



By this process a magnet lib. weight will, with due precaution, supp' rt 

 2- J lb., and the power does not sensibly diminish though the armature be 

 suddenly detached several times. It has twice the power of magnets com- 

 monly made in Britain. Magnets capable of raising 4001b. are made in 

 this way. Sir David exhihiteii two of M. Elias's magnetic horseshoe combi- 

 nations of bars, one of about 17oz. weight, and another of 12^ lb., tho 

 latter capable of supporting 150 lb. It was necessary, for their perfect action, 

 to polish the ends of the armature with two pieces of wood covered wil'i 

 emery and lead. The line joining the poles must he as perfectly hcrizont.il 

 as possible. The bars are magnetised by being moved several times through 

 a helix of copper wire, along which the galvanic current passes. 



Dr. ScoRESDY bore testimony to the great superiority of these magnets 

 to similar magnets made by regular magnet makers in this country. Bui he 

 had, after a series of niagnetical investigations (the results of which he had 

 published in 1813) made magnets nearly, if not quite, as powerful as those 

 of M. Elias. 



44* 



