Feb. 7, 1889] 



NATURE 



355 



brickwork inside the furnace or fire-box, which are duly r'e- 

 scribed by the author. The spray-injector is of course illus- 

 trated. On this depends the efficient working of the furnace. 

 The oil is blown into the furnace by means of a iteam jet. 

 Experiments have been made on the use of compressed air instead 

 of steam ; and, from what could be observed during a two 

 months' trial, the complication and cost of the extra gear would 

 not be recouped by a sufficient economy in fuel consumption. 

 The effect of petroleum fuel on the boilers, after five years' 

 experience, appears to be less destructive than when firing with 

 anthracite, which is particularly destructive to the fire-boxes and 

 tube-ends. The author states that the petroleum flame produces 

 in reality no more detrimental effect on the fire-box and tubes 

 than a wood flame, owing to the protection afforded to the more 

 important ]>arts by the fire-brick lining ; moreover, petroleum 

 refuse con ains no sulphur, which is so prevalent in all coals, and 

 so injurious to the metal of the fire-box and tubes. The eva- 

 porative value of petroleum refuse appears to be very high. 

 With an efl'ective steam pressure of 125 pounds per square 

 inch, tlie highest evaporative duty of the fuel in the author's 

 !<Komoiives has been 14 pounds of water per pound of fuel, in 

 omparison wiih the theoretical evaporative value of ij'i 

 'ii'.nd<. The aclual efficiency of the fuel is therefore nearly 82 

 per cent., the tables giving an evaporation, under the same 

 conditions, for good English coal, of I2"i6 pounds of water. 



Mr. Uiqiihari's paper will be read with great interest by tliose 

 follow ing his example in using various oils and tar as a fiiel for 

 locomotives and stationary boilers. Provided a cheap source of 

 fuel in the form of petroleum refuse or oil can be relied upon, 

 the many reasons for raising steam in this way are obvious, to 

 say nothing of ilie possibility of the machinery being kept fiee 

 from all the dirt necessitated by the use of coal on a locomo'ive. 

 The object of the paper on compound locomotives, by Mr. R. 

 Herbert Lapage, is to furnish an account of .'ome recent practice 

 in designing and working two-cylinder compound locomotives. 

 The advantages of compounding-^that is, expanding the steam in 

 more than one cylinder— is due to the difference of temperature 

 between the boiler steam and the exhaust being distributed over 

 two cylinders, with the important result that there is not so much | 

 difference as in the ordinary locomotive between the temperature 

 at the beginning and that at the end of the stroke in each cylinder ; 

 consequently there is less initial condensation and less re-evapor- 

 ation of condensed steam, and a more uniform pressure on the 

 pistons throughout the stroke ; and owing to the more constant 

 and even pressure on the pistons, the turning moments about 

 the driving axle are more uniform, giving less sudden strains to 

 the machinery generally, thereby increasing the life of the 

 machine. The fact that so little attention has until recently 

 been paid to the compounding of locomotives appears to be 

 owing to there having hitherto been considerable complication of 

 parts, in connection both with obtaining a simple device for 

 starting the engine and of equalizing the power developed in the 

 high and low pressure cylinders. These objections have now 

 been thoroughly overcome in what is known as the Worsdell 

 and Von Borries system, in which the two-cylinder compound 

 locomotive has been brought to a high pitch of efficiency. The 

 author of the paper describes a sixwheel-coupled goods engine 

 which was sent out in 1886 to the Entre-Rios Government Rail- 

 way, having been built by Messrs., Dubs and Co., Glasgow. 

 This engine was built on the compound principle, afier investi- 

 gating the excellent results obtained by the Worsdell and Von 

 liorries .system. The dimensions of the cylinders are — high 

 pressure, 16 inches diameter ; low pressure, 23 inches ; both 

 cylinders having a stroke of 24 inches ; the working pressure 

 being 175 pounds per square inch ; diameter of driving wheels 3 

 feet 9 inches. The total weight in working order is 37 tons, 

 probably having about 30 tons usefiil weight for adhesion ; the 

 cut-off of the valves in ordinary running being in the high 

 pressure cylinder 40 per cent., and in the low pressure 50 per 

 cent. Various trial trips were made with this compound on the 

 Caledonian Railway, the work doie without doubt showing 

 the power and efficiency of the engine. In the locality where 

 this engine is working coal costs at least £2 a ton ; presuming 

 an ordinary engine runs 30,000 miles a year at 25 pounds of 

 coal per mile, it will have burnt 335 tons, which, at £z per ton, 

 costs jCOyo. The compound, effecting a saving of about 20 per 

 cent., will accordingly save ^,'134 in a year. It is found that a 

 compound locomotive of less w eight can haul as heavy a train at 

 the same spred as an ordinary engine, provided the adhesion is 

 sufficient, wiih the economy of from 14^ to 20 per cent., and as 



the cost of the compound is no greater than such an engine, the 

 20 per cent, or £1^4. per year saved is a net saving to the engine. 

 Compound express locomotives working the heaviest service, 

 which run about 3000 miles per month, are found to do some 

 15 percent, more mileage between shop repairs than the ordinary 

 engines of the same size and class. 



The fact that two important papers should have been read 

 before the Institutions of Civil and Mechanical Engineers re- 

 spectively points to the conclusion that the compound locomotive 

 has out-grown the experimental stage. Jlr. Lapage says nothing 

 in his paper about the " Webb" system, and probably this is a 

 sign of the " survival of the fittest." The Worsdell engine re- 

 quires little, if any, alteration in the primary parts of an 

 ordinary engine. The number of working parts is not in- 

 creased, and the strains set up in the engine are more uniform 

 and le.ss intense than in the ordinary engine, less steam is used, 

 and therefore the boiler is not worked so hard — in fact, every- 

 thing in connection with the working of these engines points to 

 less general wear and tear of parts, and therefore longer life to 

 the macliine. 



The last paper on the list, on the latest development of roller 

 flour milling, by Mr. Henry Simon, deals with the extraordinary 

 revolution which, during the last ten years, has been in progress 

 in the manufacture of flour by the substitution of the roller 

 system for the ancient method of grinding by stones ; and the 

 object of the present paper is to give further information about 

 the subsequent development of roller flour milling as carried 

 out by the author. The completeness of the revolution that 

 has taken place is exemplified by the fact that practically, 

 in less than ten years, the machinery and methods of corn 

 milling have been radically and entirely altered at the cost 

 of an; immense amount of capital. The millstone, dating 

 from prehistoric times, has been almost entirely discarded, and 

 the miller has been constrained to unlearn the old methods, and 

 take up one entirely new, based upon very different principles. 

 The first complete roller-mill, without the use of stones, in 

 England, was built by the author in 1878 for Mr. Arthur 

 McDougall, of Manchester, and in Ireland for Messrs. E. 

 Shackleton and Sons in 1879 ! ^he first automatic roller flour- 

 mi'l in England in 1881 for Messrs. F. A. Frost and Sons, 

 Chester. The total number of complete mills, or important 

 reconstructions of old mills, executed by the author since 1878 

 amf unts to considerably more than 200, varying in cost for 

 machinery, exclusive of motive power, buildings, &c., from ;^ 1000 

 to ^^40,000 for each mill. 



As it is nearly impossible to give our readers an adequate 

 description of this class of machinery without diagrams, we do 

 not attempt the task, but recommend Mr. Simon's very interesting 

 paper to the careful perusal of all practical millers. 



iVOTE ON THE ACTION OF ACIDS UPON 

 ULTRAMARINE. 

 A T the Birmingham meeting of the British Association in 

 -^^ September 1886, I read a short paper "On the Fading of 

 Watercolouis." This was published in the Chemical News, 

 vol. liv. 



Observation and experiments had led me to the conclusion 

 that water-colour drawings in which ultramarine was mixed with 

 reds for the representation of purple and gray tints such as are 

 seen when viewing distant mountains, the shadows of clouds, 

 and other luminous shadows, the colours are liable to suffer 

 from the action of acids such as might be found in the drawing- 

 paper, or in the damp atmosphere of towns where much coal is 

 burnt. The general opinion of artists is one which I believe 

 does not coincide with this view. The same series of experiments 

 had shown that under ordinary circumstances indigo was a colour 

 ot great stability compared with many other pigments, and this 

 again was in conflict with the experience of artists. It is not 

 impossible to explain how we have arrived at such different 

 views, and though it would be inconvenient to enter into an ex- 

 planation in full, it may be considered as within the scope of this 

 paper to record the fact that the colours were washed u |ion the 

 best drawing-paper, di ied in a subdued light, and not exposed 

 to the conjoint action of damp and sunlight. 



The matter in hand is the question of the stability of ultra- 

 marine in presence of acids. In an old work by .M. Constant de 

 Massoul, translated into English in i8i2, entitled " .\ Treatise 

 on the Art of Painting and the Composition of Colours," ashort 



