January 2, 1914 THE COLLIERY GUARDIAN 43 LAMINATED GEARS. We have recently had the opportunity of inspecting a number of wheel gears, constructed on a new principle, that seem to offer several advantages. In the manu- facture of these gears, instead of taking a solid blank From Total cargo. Total 1 bunker. 1912. 1913. 1912. 1913. Tons. Tons. Tons. Tons. Bristol Channel ports 286,613 284,266 19,833 19,618 North-western ports 265,526 237,794 64 296 58,703 North-eastern ports 776,306 660,753 22,216 26,821 Humber ports 272,861 208,942 15,849 12,670 Other ports on east coast 13,938 10,450 8.727 9,055 Other English ports 2 877 2,186 3,467 4,237 Total from England and Wales .. 1,618,121 1,404,391 134,388 131,104 Ports on east coast of Scotland 112,109 103,961 18,563 18,793 Ports on west coast of Scotland 123 207 104,792 34054 32 323 Total from Scotland 235,316 208,753 52,617 51,116 Irish ports 103 — 3,598 1,846 Total from United Kingdom 1,853,540 1,613,144 190,603 184,066 The destination of cargo shipments was as follows and machining the teeth from same in a milling or shaping machine, a number of discs of thin metal are produced in an ordinary press, and the discs have teeth punched on their periphery in accordance with require- ments. These discs are placed side by side and clamped together by rivets, thus forming a gear wheel of the requisite thickness. The discs may be formed with a bore for the spindle and provided with key or spline- ways, or arranged to fit over a spider. In punching the discs, the rivet or bolt holes can be formed at the same time as the bore and key way. These discs are located on the tooth-notching machine by the bore and the keyway, thus every disc is identical as regards diameter of pitch circle, shape of tooth, and phase of the teeth relative to the key way and bolt holes. However, in building up a wheel, all the plates do not have the same tooth phase, for every plate has its teeth phased one-half tooth from the next plate, which results in the halving of the virtual pitch and the doubling of the contacts. In the case of a large wheel, the plates are mounted on a spider by spigoting them on the same and bolting or riveting through the holes produced in the plates, and the utilisation of a spider allows of a gear being pro- duced of any size, as the limiting factor is the spider, and not the plates. In cases where it is essential that these laminated gears, as they are called, should have hardened teeth, there is no danger of distortion, for the reason that in the hardening process the plates can be packed on a mandrel, so as to form a long pinion with the teeth in line. Between each plate is inserted a washer of metal, that may be four, six, eight or 12 thousandths in thickness, in accordance with requirements ; this leaves a clearance for the teeth to pass without friction. One advantage claimed for these gears is their silence. With the laminated gears, owing to the staggering of the teeth, the power of the blow is halved, and, conse- quently, there is less direct noise, but the “ring” is entirely eliminated by the laminations, for if one of these gears be suspended and struck by a hammer either on the face or the side, the sound produced is of the same kind as would be obtained from a disc of lead under the same circumstances. A factory for the production of these gears is in Sedgley-road, Owlerton, Sheffield. The inventor of this principle is Mr. A. E. Terry, of Messrs. Herbert Terry and Sons, the well-known spring manufacturers and steel stampers, of Redditch, and a private company has been formed amongst various gentlemen connected with the financial and steel interests in Sheffield and various engineering interests in the Midlands. The works have been equipped under the technical direction of Mr. Terry, with a suitable plant of presses and other machine tools and appliances required for the purpose in view. The gears would seem to be applicable to numerous branches of what may be termed general engineering, and to have a distinct opening in mines, where noiseless working is often a matter of importance. Among other types of machinery falling within this class are geared pumps, haulage engines, coal-cutting machines, exhaust steam turbines, &c. Almanacs and Diaries have been received from the “ Ceag ” Electric Safety Lamp Company Limited, W. J. Gilo ver and Co., Partridge and Cooper Limited, Diamond Coal Cutter Company, George Cradock and Co. Limited. COASTWISE SHIPMENTS DURING NOVEMBER. According to the monthly coal tables, the following were the quantities shipped coastwise during the month of November:— To ports in England and Wales....... Scotland................ Ireland ................ Nov. 1912. Nov. 1913. Tons. Tons. 1,350,410 ... 1,174,144 94,423 ... 89,914 408,707 ... 349,186 Shipments to London totalled 739,946 tons. LAW INTELLIGENCE. SCOTTISH COURT OF SESSION. OUTER HOUSE.—December 17. Before Lord Hunter. A Failure to Give Written Notice. E. H. Blair v. Dalmellington Iron Company Limited.— This was an action by Edward Hunter Blair, of Brownhill and Blairquhan, Ayr, captain, Royal Navy, residing at Blairquhan Castle, near Maybole, against the Dalmellington Iron Company Limited, Dunaskin, Ayrshire, for .£250, being a year’s rent of the minerals under the pursuer’s farm of Grimmet, Straiton, Ayrshire. The pursuer by lease dated in 1909 let the minerals to the defenders, with power to them to terminate the lease at Martinmas 1911. The lease stated that the proprietor did not warrant the existence or quality of the minerals let. The defenders made bores and found no workable coal, and they said the defenders’ representatives knew that the works were abandoned. The Lord Ordinary in the course of his opinion said the lease contained a declaration that if the lease was to be terminated in 1911 three months’ previous notice in writing must be given, “ and also at the expiry of every third year from and after said last-mentioned term upon giving to the proprietor in every case six months’ previous notice in writing as aforesaid—this right and liberty being deemed to supersede any right which might have been competent to the tenants to renounce the lease on the ground of the minerals not being workable to profit or otherwise.” As a result of bores sunk by them prior to May 1910, the defenders were satisfied that coal did not exist under the land that could be worked to a profit. They communicated the journals of the borings to Mr. M’Lauchlan, a mining engineer, who represented the pursuer. He also was satisfied that the minerals were unworkable to profit. The defenders as a result of the proof asked for absolvitor on two grounds—first, that the communications with Mr. M’Lauchlan amounted to notice; and second, that the delay in making the claim barred the pursuer from insisting therein. So far as the first of these pleas was concerned, it had not been proved that Mr. M’Lauchlan was the agent of the pursuer, i.e., agent in the sense that notice to him would have been equivalent to notice to the pursuer. No letter sent to Mr. M’Lauchlan gave notice in terms to terminate. As regarded the plea founded on delay, it was true that during the period for proving the field no demand was made for a statement of coal worked with a view to fixing royalties payable. This was explained by the circumstances that both the pursuer and his agent knew that no coal or other mineral was being worked. He did not attach much importance to the demand for the fixed rent not being made at the end of the first half-year, but only after the completion of a full year. He had no option but to give decree in terms of the conclusions of the summons. It is announced that arrangements have been concluded under which the two concerns of Lassen and Hjort and Water Softeners Limited will henceforth operate in the British Isles as a joint concern under the title of United Water Softeners Limited. Messrs. Water Softeners Limited, are the proprietors of the recently introduced “Permutit” regenerative process. Letters to the Editor. Phe Editor is not responsible either for the statements made, or the opinions expressed by correspondents. All communications must be authenticated by the name and address of the sender, whether for publication or not. No notice can be taken of anonymous communi- cations. As replies to questions are only given by way of published answers to correspondents, and not by letter, stamped addressed envelopes are not required to be sent. THE HOME OFFICE AND ELECTRIC LAMPS. Sir,—On looking up the conditions for the Home Office competition for miners’ electric lamps, I find that one of the conditions was that “ the lamp must be capable of giving an amount of light not less than 2-candle power continuously for 10 hours ” ; and that regard would be directed to :— a. Initial cost of lamp. b. Cost of maintenance. c. Convenience in handling. d. Weight of lamp. The Government requirement for portable electric miners’ lamps is that they shall give 1-candle power for nine consecutive hours. We have been making enquiries into this matter, and find that the electric lamps on the market to-day cannot reasonably be said to comply with the above require- ments ; as a matter of fact, we find on taking lamps which have been supplied by people who advertise having got prizes at the Home Office competition, that their electric lamp, instead of giving 2-candle power or even l|-candle power, is giving less than 1 -candle power, and we have carried out tests on a vast number of bulbs and cannot find on the market to-day a practicable 2-volt bulb and accumulator giving 1-candle power for nine consecutive hours—the candle-power ’ only being got by overmanning the bulb, which cannot be done in general practice without fearful expense, as bulbs under these conditions have such a short life. If, therefore, the Home Office carry out their powers to impound lamps and reject such as do not meet the Home Office requirements, it would appear that the electric lamps in this country are subject to rejection. E. A. Hailwood, Manager for Ackroyd and Best Ltd. Morley, near Leeds, December 24, 1913. SPONTANEOUS COMBUSTION IN COALMINES. A Digest of Evidence before the Committee. {Continued from page 1337, vol. cvii.) PROF. BONE. Prof. William A. Bone, professor of chemical technology at the Imperial College of Science and Technology at South Kensington, gave evidence on June 10. He said he had not done any practical experi- mental work himself on the spontaneous combustion of coal, but he had read in detail the principal experimental researches which have been made on the Continent and in America, and also the opinions of one or two leading English authorities. These, together with his knowledge of the action of surfaces in regard to combustion, had enabled him to arrive at certain general views rather tentatively. There were matters with regard to which it was desirable that further experiments should be made. He next referred to the researches of Richter, Fayol, Threlfall, Prof. Vivian Lewes, and. Parr and Kressmann. The latter he regarded as a very well carried out investigation on the whole. The most important of their general, conclusions are, firstly: “ The oxidation of coal is continuous over a wide range of time and conditions, and begins with the freshly-mined coal at ordinary temperatures. A number of oxidation processes are involved, which are more or less distinct in character, some being relatively slow and moderate in form, while others are rapid and vigorous in action.” Prof. Bone thought this a reasonable surmise, although they did not discover or differentiate between the various possible oxidation processes in the coal substance itself, and there was nothing in their experiments which would enable one to say definitely that there were different processes at work other than the obvious difference between the oxidation of asso- ciated pyritic matter and the oxidation of the coal substance itself. Then they said, secondly: “ In general it may be said that for a given coal a point exists, as indicated by the temperature, below which oxidation is not ultimately destructive. The continuance of this point is dependent upon certain accessory conditions ; if these conditions are withdrawn the oxidation ceases. On the other hand, above this critical point, which is best indicated by temperature, oxidation is ultimately destructive, and is characterised by the fact that it does not depend for its continuance upon external conditions, but is self-propelling or autogenous.” Then they say: “ The point of autogenous oxidation, while varying for different conditions, may be indicated by temperatures of the mass ranging from 140 to 160 degs. Cent, in an atmosphere of oxygen, or approximately between 200 to 275 degs. Cent, in oxygen diluted with nitrogen, as in air, depending to a great extent upon the fineness of division. The phenomenon of fire or actual kindling