194.8.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



or fully 70 percent. The superintendent of the machinery assured him 

 ihat the engine had never cost Ihem £12 a-year since it was erected. Its 

 usual speed was about 5 strokes per minute ; but it was capable of work- 

 ing at 7 strokes per minute without any concussion in the descending 

 column, the duty actually done beiug equal to 163 horse-power: — Area of 

 plunger 9-021 feet X 10 feet X 7strokes= 673-41. 673-41 X C2-5 x 132 = 

 ^ aiioo w' = 163 horse-power. The author concluded by remarking that, 

 in (his case as in all others when water acts by its gravity or pressure, 

 those machines do the best work when the water enters the machine 

 without shock or impulse and quits it without velocity. They thereby 

 obtain all the available power that the water will yield with the least loss 

 of effect; and this result is best accomphshed by making the pipes and 

 passages of suSicient and ample size to prevent acceleration of the hydro- 

 static column. 



'^ Analysis of Wrought-Iron produced by Cementation from Cast-Iron." 

 By Professor INIiller. 



It is to be noticed that considerable change in the specific gravity oc- 

 curred in the iron after cementation : it was forged, and then found to 

 have increased in density ; the brittle iron had a specific gravity of 7-684, 

 the malleable 7-718. The results of analysis were briefly these : — The 

 quantity both of carbon and silicon are materially diminished by the 

 cementation, though still the propoi-tion of both is materially gi-ealer than 

 in good bar-ii-oa. It also appfars that the portion of carbon which is in- 

 soluble in acids is partly the same both before and after the iron has been 

 rendered malleable, the dimiuuiion being confined almost to that portion 

 of carbon which was chemically combined with the metal, and which, 

 therefore, would be in a state for propagation through the mass more 

 readily by cementatio:i. 



'- On the Drainage of a Portion uf Clmt-3Ioss." By G. \V. ORMtROD. 



The SHf/rtt-e of the moss varies from 80 feet to 100 feet above the sea 

 level ; its bottom at the deepest part is 100 feet below the sea line. Part 

 of this moss is now being laid dry by means of open drains, under the 

 directions of Mr. Ormerod. After cutting the drains, the level of the peat 

 falls rapidly ; near the main leader it sank perpendicularly S ft. 6 in. in 

 nine months, and in one part 2 ft. 6 in. in a single week. 



" Extraction nf Silver from some of its Ores by the Wet Way, with a 

 Notice of a Process as a Substitute for that of Liquation." Communicated 

 by Dr. Pi-rcy. 



This communication proposes to treat silver ores with hyposiilphate of 

 lime and chloride of lime ; and from experiments detailed by Dr. Percy 

 there appears every i-eason to believe that these substances may be em- 

 ^ployed economically, and both gold and silver extracted by an easy and 

 effective method. A process as a substitute fur that of liquation was also 

 suggested. Mr. Hunt proposed, from the importance in a practical point 

 of this communication, that it he printed entire in the volume of Ti-ausac- 

 tions. Col. Vorke seconded this proposition ; and it was adopted. 



" A new Hydrographic Map nf the British Isles," by Herr Petirmann, 

 was exhibited. 



On this map about 1,550 rivers are distinguished by names, 480 lakes 

 and ponds, and 40 waterfalls ; the canals with their altitude, as well as 

 that of the rivers and lakes, and the great drains in the fen districts It 

 was stated that there were 20 rivers in England, 10 m Scotland, and 10 in 

 Ireland, each draining 500 square miles and upwards. Of these — 



18 drain an area each ^ .''lOO to 1,000 square miles. 

 14 „ — 1.1)110 „ 2.1I0II „ 



8 „ = a.UOJ „ lO.UUU „ 



These last eight are — The 



Huniber (including Trent and Ouse) to Spurn Point 9,.550 



Severn (to Flat Holmes) 8, .580 



Shannon (10 Loop Head and Kerry Head) .. .. 6.114(3 



Thames unclutiing Wedvvayi to Note Light 6.1(50 



Uarrow .. .. .. .. , .. ., .. .. .. ;1.410 



Great Ouse L'.KfiO 



Bann 2.:U^ 



Tay, as far as Rhynd 2,250 



The river Amazon drains a tract of 2,275.000 squai-e uiiles. 



" On a New Element of Mechanism." By Mr. R. Roberts. 



The writer explained the construction of a contrivance by which he 

 effected in a very simple manner movements for which more complicated 

 mechanism w'as frequently employed. The model consisted of a steel 

 stock-shaft, on vthich were fitted two brass discs in such a way as to be 

 kept steady. One of the discs had eleven teeth rounded at the top and 

 bottom in its circumference, and was placed on the body of the shaft. 

 The other disc, which was rather the larger, was in the eccentric position 

 of the shaft, with its face to that of the toothed di.-'C. The plain disc liad 

 four studs rivetted into it at equal distances from each other and at such 

 cistances as to admit of their being brought successively, by the revolution 

 of the eccentric, to the bottom of the hollows in the toothed disc. The 

 following movements may be effected by this model : — viz., if the shaft 

 be held stationary and the discs be made to rcvi.lve upon it, one of the 

 discs will make twelve revolutions wliilst the other only makes eleven. 

 Again, if the toothed disc tje held whilst the shaft be made to revolve 

 twelve times, the plain disc will revolve, in the same direction, one revolu- 

 tion only ; and if the plain disc be held, the toothed disc will perform one 



315 



revolution in the contrary direction, for eleven revolutions of the shaft. It 

 would be evident that almost any other number of revolutions may be pro- 

 duced by empkiyingasmaller number of studs, not fewer than three, which 

 will not divide the number of teeth in that disc. The idea of this novel 

 element in mechanics was suggested to Mr. Roberts by a dial movement 

 in an American clock. 



MINTS.* 



The subject of mints is one on which there is little printed, but 

 Major Smith, of Madras, has brought out a considerable book. This 

 work is mostly directed to the subject of mint accounts, but with 

 this object a, close investigation is necessary into the processes 

 aifecting the condition of the precious metals in the operation of 

 coining, and this may be found of interest. Major Smith's great 

 purpose is to establish that no loss of value of gold or silver can or 

 does take place in coining, and that there is therefore no difficulty, 

 under a proper system of management, of providing an adequate 

 check. He says — 



VVe consider it beyond doubt, judging from the results of actual experi- 

 ence, that there ought to be no loss whatever by the process of conversion, 

 in any of the Indian Mints; on the contrary, as we have elsewhere ex- 

 plained, there ought to be a small surplus in the out-turn. In the discus- 

 sion, therefore, of the duties and responsibilities of the different ofScers 

 of the establishment, we shall consider this as being admitted, because 

 our object is to determine what the requisite checks are to insure the busi- 

 ness being properly executed ; not what may suliice if it be imperfectly 

 done, or slurred over. 



Before proceeding, however, it may be advisable that we should lirst 

 notice and obviate a misconception which has been suggested to us in 

 reference to the above assertion, as it strikes at the very root of all the 

 benefit of the important principle involved in it. It has been said, that it 

 may be very true there ought to be no waste, or even a slight surplus in 

 the re-delivery of the precious metal entrusted to a Mint, provided it were 

 possible to extract all the particles from the mass of refuse wherein they 

 are buried ; that by pushing the recoveries to an extreme length, in de- 

 fiance of all real economy, it may be in fact possible to exhibit a trifling 

 over-plus, though the cost of the extraction of the last particles may have 

 far exceeded the value of the metal ; but that unless this reckless contempt 

 of true economy be systematically persevered in, as it is clear that a cer- 

 tain amount of bullion must, of necessity, be allowed to remain untouched, 

 on account of the expense of extraction, a waste must be unavoidable ; so 

 that however true in theory, it must be a fallacy in practice to say, that 

 there ought to be a nelt surplus of delivery, and an actual bona fide excess. 

 This argument is, however, based upon a misapprehension of the truth it 

 is intended to oppose, for the assertion is not, that there should be no 

 metal not recovered, but that there should be no metal lost whose existence 

 could not be proved, and its value recovered, if necessary. Further, that 

 as a matter of actual practice, there ought to be a nelt surplus of delivery, 

 including the panicles in the dros.ses, whether they be recovered therefrom 

 or whether they be not, which is totally immaterial to the question ; to 

 which it may be added, that this excess ought to be so much larger than 

 the value of all the particles which are not extracted from the refuse, that 

 even taking the matter in the sense in which it is viewed in the objection, 

 the assertion still remains practically true. 



The principle and the practice we contend for is, that the out-turn of a 

 Mint in coins, bullion, and drosses, ought to be exactly estimated, and 

 compared with its receipts ; and we aflirin that if this be correctly done, 

 and the duties of the Mint have been strictly and faithfully performed 

 throughout, the former ought to exceed the latter, whenever the bullion is 

 debited at the '• trade Assay." Which being the case, we are of opinion 

 that, as a matter of system, the comparison ought to be made, and the 

 check thereby established, in prefereme to the more lax proceeding of 

 omitting the comparison, and writing uli' all deficiencies to profit and loss 

 as '• unavoidable waste in the operalioiis of coinage." The extent to which 

 the extraction of the bullion out of Hie drosses ought to be carried, is 

 another and a very simple question ; tiie answer to which obviously is, thai 

 it should be carried so far, and no farther, 'ban it would be attended by a 

 clear profit to do so. In this way it is that the business is carried on in 

 Madras, the refuse, when no longer capable of being " recovered" on 

 account of Government with protii, being sold, and the proceeds carried 

 to account ; and it is according to tins scheme of practice, that the actual 

 results which have been referred to have produced a uett surplus amount- 

 ing to .j^ per niille. 



If, however, there ought to be no deficiency of the precious 

 metals, it does sometimes happen : it seems that coins are sent out 

 of tlie mints too good. Thus it is said — 



We have beei; informed, that in the year 1845, the coins issued by the 



* "Observations on the Duties and Responsibilities involved in the Management of 

 Mints; chiefly with reference to the Rules and Practice of those of India. With sug- 

 gestions for their Improvement." By Major J. T. SMriH, H.E.I.C. Engineers, F.R.S., 

 A.I.C.E., Master of the Madras Mint. Madras, 1848. 



41* 



