1849.J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



157 



weigh more than seven pounds ; this, in carriage, would give Benzole an ad- 

 vantage of twenty-eight to one over coal as a source of light. 



In the discussion which ensued, high encomiums were passed upon the 

 talent and patient labour exhibited by Mr. Mansfield in the investigation of 

 this important subject, vthich promised to lead to most remarkable results, 

 as an extension of gas lighting to positions where it had not before been con- 

 sidered applicable. 



April 24. — William Cubitt, Esq., V.P., in the Chair. 



The paper read was " On the Construction of Locomotive Engines, espe- 

 cially those modifications which enable additional Power to be gained without 

 materially increasing the Weight, or unduly elevating the Centre of Gravity." 

 By Mr. T. R. Crampton, Assoc. Inst. C.E. 



It was contended, that the durability of the working parts of the engine, 

 the stability of the permanent way, and the freedom from oscillation so 

 essential for the comfort of travelling, all depended upon the steadiness of 

 the engines when at high speeds. This consideration led the author to 

 introduce several modifications of the ordinary construction of locomotives; 

 the driving-wheels were removed from the centre of the engine to behind 

 the fire-box, placing all the weight on and between the extreme points of 

 support. The centre of gravity was so reduced, that on the narrow-gauge 

 railways, the angle of stability equalled that of the broad-gauge engines. 

 All the moving parts of the machinery were removed from beneath the 

 boiler and placed on the two sides, within the easy inspection of the work- 

 men, and enabling the repairs to he eflfeoted with ease and dispatch. These 

 dispositions had the effect of enabling a larger amount of heating surface to 

 be given in the boiler, within a certain length of engine, than even in the 

 larger class of engines of much heavier weight; thus, in fact, simultaneously 

 concentrating the power and reducing the weight. 



Upon this principle, snme engines of a smaller class had been constructed, 

 containing the water and coke tank within the same frame and on the same 

 wheels as the boiler; this arrangement became practicable in consequence of 

 the removal of the machinery from beneath to the two sides, leaving a con- 

 venient space for the tank, and the whole weight was placed within the 

 extreme wheels, reducing, at the same time, the centre of gravity of the 

 mass ; for it was argued, that the two points of importance were to place 

 the weight on and between the extreme wheels, and to bring the line of 

 traction identical with the centre of gravity of the moving mass. 



These positions were illustrated by a set of diagrams, showing the various 

 constructions of engines that had been induced by the requirements of 

 railways, and the demands, whether for economy of fuel, or increase of 

 speed; and demonstrating that the class of engines having the driving- 

 wheels under the centre of gravity of the boiler, was that which oscillated 

 most at high speed ; but that the class possessing the greatest amount of 

 steadiness, was that in which the driving-wheels, and the weight which must 

 accompany them, were removed to the hinder extremity of the engine. 



The paper gave the details of the various changes, and the arguments for 

 and against each class of construction, and the author requested, that if his 

 reasonings were proved to be fallacious, some rules should be laid down 

 for guiding the general practice of engineers in the construction of locomo- 

 tives. 



In the discussion which ensued, the arguments chiefly went to show, that 

 it was the length of the base, or the area of the space covered by the 

 wheels, rather than their position, and that of the weight upon them, that 

 induced steadiness. On the other hand, it was contended, that although 

 additional steadiness bad been obtained in the old engines by thus extending 

 the length of the base, yet that if, as had been shown to be practicable, a 

 greater degree of steadiness could be obtained from an engine of less length 

 between the extremities, when the driving-wheels were removed from the 

 centre to the extremity, it was manifestly advantageous to adopt such a form 

 of construction. This was practically instanced by a small engine, of less 

 than nine feet between the centre of the wheels, running with perfect 

 steadiness at high speed ; whereas, with the old class of engines, it had 

 always been considered necessary for safety to have at least eighteen feet 

 between these centres. 



SOCIETY OF ARTS, LONDON. 

 April 11.— B. RoTCH, Esq., V.P., in the Chair. 



"On the Oxalis Crenata." By Baron De Sharce. Specimens were ex- 

 hibited. 



The Oxalis Crenata has been known to the scientific agriculturists of 

 Europe for some years : it is a tubercle the culture of which, however, upon 

 a large scale has been little practised. This tubercle is stated by Baron de 

 Suarce (who has cultivated about two acres and a half of it upon his own 

 estate in the south of France) to possess a larger degree of nutriment than 

 most of the farinaceous plants which form the basis of human food in our 

 climate. The total weight of the crop produced upon the above land by 

 the Baron was ten tons, from which three tons of flour was obtained. From 

 the steins of the plant, which may be cut twice a-year, and can he eaten as a 

 salad or spinach, 90 gallons of a strong acid was obtained, which, when 

 mixed with three times its bulk of water, was well adapted for drink. The 

 acid, if fermented and brought to an equal degree of acidity with vinegar, is 

 superior to the latter when used for curing or preserving meat, as it does not 

 render it bard, or communicate to it a bad flavour. The flour obtained from 



the Oxalis Crenata is superior to that obtained from the potato, maize, or 

 buckwheat, as it makes an excellent light bread when mixed in the pro- 

 portion of one-fourth corn flour : this is not the case with potato, maizr, 

 or buckwheat flour. The Baron concluded his paper by expressing his wil- 

 lingness to make any further communication to the Society on the subject, as 

 he would consider it a great happiness to be enabled, with their aid, to in- 

 troduce into England the culture of a tubercle which seems destined to be- 

 come a resource of food for the lower classes, more precious perhaps than 

 even the potato. 



In reply to a series of questions, the Baron stated that the Oxalis Crenata 

 came originally from South America ; ihat it is hardy, and unatfected by the 

 change of temperature; and grows readily in any soil, it being diflicult when 

 once introduced to eradicate it. 



"On the importance of the Animal Refuse of Towns as a Manure, and the 

 method of rendering it available to Jgrtcttltural purposes." By Dr. Atres. 



The author commenced his paper by calling attention to the necessity of 

 preserving the animal refuse of towns, and the importance which is attached 

 to it in China and Flanders, in many departments of France, Tuscany, &c. ; 

 and also to the various forms in which it is applied to the earth. Having 

 alluded to the importance of this subject in connection with the improve- 

 ment of the sanitary condition of towns, and the injurious effects upon the 

 inhabitants of London in particular, by allowing the putrid matter to be car- 

 ried into the Thames, there to be tossed upon the waves, and left exposed 

 upon the shores at each retrocession of the tide, — he proceeded to consider 

 the contents of the cesspools of London alone, which he has calculated can 

 not yield less than 46,500 tons of perfectly dry matter annually — a quantity, 

 according to the analysis of Liebig, suflicient to fertilise at least 1,000,000 

 acres of land, and the monetary value of which cannot be stated at less than 

 340,000/. Having next alluded to the plans which have hitherto been pro- 

 posed for drying and rendering this great mass of matter portable and avail- 

 able for agricultural purposes. Dr. Ayres proceeded to describe a plan which 

 he has recently patented for effecting so desirable an object. His process, he 

 stated, essentially depends on the fact that all the gaseous and volatile pri)- 

 ducts of putrefaction are combustible, and are resolved into the ordinary 

 products of combustion when carried over any incandescent surface, or over 

 or through burning fuel when mixed with atmospheric air. Thus ammonia 

 is resohed into nitrogen and water; sulphuretted hydrogen into sulphurous 

 acid and water; carburetted hydrogen into carbonic acid and water; and 

 phosphoretted hydrogen into phosphoric acid and water. The volatile orga- 

 iiic matters associated with the gaie^ are completely destroyed ; carbonic 

 acid alone passes through the fire unchanged. All these gases, with the 

 exception of ammonia and carbonic acid, exist only in very small proportions 

 in putrescent animal matter. U follows from what has been stated, that all 

 the volatile products of putrefaction are thus resolveable into the ordinary 

 products of combustion, which are well known to be innocuous. It suffices 

 to conduct these gases and vapours through a fire to effect their entire 

 decomposition and destruction. The apparatus by which this process may 

 be worked is susceptible of many modifications, but those to which he parti- 

 cularly desired to direct the attention of the Society, consist in drying the 

 animal refuse by the application of heat, either obtained from steam-pipes or 

 otherwise, and at the same time destroying the volatile products of putrefac- 

 tion by burning them. 



A lengthened discussion followed the reading of the paper, at the close of 

 which the thanks of the meeting were presented to Dr. Ayies for bis com- 

 munication. 



April 18.— T. WEBsTitR, Esq., F.R.S., V.P., in the Chair. 



"On the supposed Influence of Oxygen on the Colour or Tint of Flint 

 Glass." By F. Fellatt, Esq. 



The author in commencing his paper stated that the remarks contained in 

 the same are entirely the result of experience in the manufacture of glass in 

 large quantities, it being only under such circumstances that many of the 

 changes there noticed can be observed, because they are so minute that in 

 dealing with small quantities their occurrence would not be perceptible. In 

 speaking of white glass the term is comparative, as no glass is perfectly 

 colourless, and to the practised eye of the glassmaker there exists no two 

 pieces of the same tint or shade: the word colour therefore is used to denote 

 that particular tint or shade, whatever it be, which all white transparent 

 glass possesses. With these remarks, the author proceeded to consider the 

 action of oxygen as affecting the colour of flint glass in two distinct particu- 

 lars — first, its action upon the glass mixture during its melting or founding, 

 whilst in a state of fusion ; and, secondly, during its annealing or gradual 

 cooling. 



The constituents of flint glass are silica, lead, carbonate of potash, and 

 nitrate of potash. The silica is found sufliciently pure as fine sand which 

 abounds in some districts ; that from Alum Bay, Isle of Wight, is much es- 

 teemed. The protoxide of lead (litharge), or the deutoxide (red lead), is the 

 state in which the lead is used; and the potash is the ordinary curl and 

 nitrate of potash of commerce. These, when mixed in certain proportions 

 and subjected to a strong heat for sixty or seventy hours, produce flint glass. 

 The purer the material, the more transparent the glass : but although all the 

 materials be chemically pure, a colourless glass is not the product, — owing 

 to some chemical change which takes place during the melting, the glass \% 

 tinted with green. This is generally stated to arise from the presence of 

 oxide of iron, but the author believes that in must instances it is owiu); to 



