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TUESDAY, SEPTEMBER 17.

The following Papers were read :

1. The Field Telegraph in the Chitral Campaign.

By P. V. LUKE, Deputy Director-General of Indian Telegraphs.

The field telegraph required for the army in India, for the many small expeditions in which it is so often engaged, is furnished by the Civil Telegraph Department. The department must be ready therefore at all times to meet any demands made upon it. A suitable equipment has been designed, and a stock is kept at convenient depôts at various points on the frontier; this enables an immediate start to be made with the construction of the field telegraph in any operations, while for prolonged operations the whole resource of the Civil Telegraph Department can be made available.

All the equipment is arranged for 'pack' carriage; the maximum weight of any one package is fixed at 80 lbs. (one half the load a mule will carry). After every campaign a full report is sent in of the working, and any defects brought to light are dealt with at once.

The receiving instrument used is a sounder similar to the one used throughout India, only reduced in size. It is fitted on a base-board with a small Siemens relay and a key, with connections so arranged that it can either be worked 'direct' or as a local. A perfect portable battery has still to be designed; at present the socalled 'dry' pattern is used.

The unit of office equipment, or total needed for one field office, which includes tents, &c., comprises seven mule loads, but it can be compressed to four loads if necessary for an emergency and for temporary work. Telephone apparatus is always included. The line wire employed is iron wire weighing 300 and 150 lbs. per mile, and stranded hard copper wire weighing 80 lbs. per mile; light field cable is used for certain purposes. For poles, where possible, the resources of the country passed through are utilised; but for bare country, iron poles are carried. They are tubular sheet iron in three pieces, fitting telescopically; the total height is 18 feet, and weight 40 lbs., the packages being 5 feet long. At twenty to the mile they will carry three wires, one in a cap, the other two on insulators.

The rate of construction depends on the transport, labour, and character of country. In the Waziristan campaign a single wire line was put up at rate of nine miles a day for five consecutive days.

Special arrangements for rapid repair are always made; for this purpose it is necessary to have a telegraph office at every ten miles, with a trained line staff. For the signalling staff, trained British soldiers are mainly used; these men are employed at other times at different telegraph offices throughout the country, usually where their regiments are quartered.

The Field Telegraph forms a distinct department in the field, under a civilian telegraph officer appointed by the Director-General of Telegraphs, and taking his orders from the chief of the staff.

Information of the siege of Chitral came from Gilgit over the line which was only completed in 1894. This line is carried over two passes, one 11,600 feet, the other 13,500 feet above sea level, where the snow lies from 10 to 18 feet, yet it worked well all through the winter. The staff at the observation stations close to these passes are entirely cut off from the rest of the world except by wire for seven months in the year. The place selected as the base of operations was Holi Mardan; best material for a two-wire 200-mile line with twenty offices was at once collected, together with the necessary staff for constructing and working. From this point the wire was pushed on as fast as possible, and a field office was opened on the Malakand Pass a few hours after the battle. At first it was a single-wire line, but it was afterwards made a three-wire line as far as the Swat Valley, then a two-wire to Dir, and finally one-wire to Chitral Fort.

Great difficulties with transport occurred at Lowari Pass, owing to the pass

not being passable for camels; but for this the wire would have been into Chitral by May 12-as it was it did not reach there till midnight of the 17th.

On account of the scarcity of timber it was necessary to use iron poles very extensively; at the Lowari Pass, however, there is a fine pine forest; wooden poles were afterwards used.

After May, cutting the wood became very frequent, and even very difficult to stop.

After the start the traffic, which was exceedingly heavy, was dealt with, with but little delay; in April 24,370 and in May 58,935 messages were dealt with, and their length was much above the average. Shortly after the Malakand fight, by clearing the line right through to Simla, the Commander-in-Chief was enabled to talk direct to General Low, and in spite of heavy rains at the time the communication was excellent.

To give some notion of what was accomplished, it may be stated that a telegram dated Chitral Fort, May 19, was published in the London papers of the same date.

The Telegraph Department also assists in defending camps by running wires round the camp, so arranged that an alarm is at once given by the ringing of a bell in the Quarter Guard should a night surprise be attempted, and in many other ways much aids and assists the military authorities.

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Medals and decorations are given to the staff at the conclusion of the campaign.

2. A Movement Designed to attain Astronomical Accuracy in the Motion of Siderostats. By G. JOHNSTONE STONEY, F.R.S.

3. On Modern Flour Milling Machinery. By F. W. TURNER.

4. On the Production of Letterpress Printing Surfaces without the use of Types. By JOHN SOUTHWARD.

The author describes a recent invention, known as the 'Linotype' Composing Machine, which enables certain kinds of letterpress printing—namely, the plain text of books and newspapers-to be done without the use of types. The invention constitutes a remarkable improvement upon the present methods of typography, which, in all essential particulars, have remained unchanged during the last four and a half centuries.

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Hitherto, letterpress printing surfaces of the kind referred to, or those representing alphabetical characters, have been formed by combining together, or composing-to use the technical term-movable interchangeable types, having cast upon them in relief the characters they are to represent. In the Linotype system, instead of such types being composed, matrices, corresponding to them to the extent of having characters engraved upon them, but in intaglio, are set up. When a sufficient number of matrices to form a line of given length are assembled, they are cast from, and a bar of metal formed, which has a surface in relief, precisely equivalent, for printing purposes, to one consisting of separate types. A large number of newspapers in this country, and especially in the United States, have within the last year or two adopted this system, and entirely dispensed with types for the whole of their contents, with the exception of what are called 'displayed' or ornamental advertisements. Many books have lately been printed in

the same manner.

The Linotype machine comprises mechanism for-first, composing the matrices; second, casting from them when they complete a line of reading matter; third, distributing them back again to their proper magazines in order that they may again and again be used to form succeeding lines. These three operations are carried on concurrently; that is to say, while the matrices for one line are being composed, those of the previous line are being cast from, and at the same time the matrices for the line before that again are being distributed. The result is that

lines of, as it were, stereotyped matter are produced much more rapidly than the most expert compositor could put together the types or letters of which they

consist.

The matrices are stored in the upper part of the machine in an inclined magazine with compartments in which the matrices are assorted in a somewhat similar manner to that in which the types are contained in the boxes of an ordinary 'compositor's case.' The matrices tend to slide downward by gravity out of this magazine.

In the lower part of the machine there is a keyboard and connected mechanism, whereby, each time a key is depressed by the finger of the operator, a single matrix, bearing the character corresponding to the key, is permitted to fall out of the mouth of the magazine through vertical channels. The matrix then comes in contact with an inclined travelling belt, which carries it and succeeding matrices downward, one after another, into the 'assembling block,' where they are composed, or set up side by side in a row.

After the line is thus composed it is transferred to the casting mechanism, by which the metal is injected into the incised lines or letters of the matrices. The casting box or mould provides for a bar being cast similar in height and body to a line of types. It is finished by knives, which shave off the feet and trim or plane the sides. One after another the line bars are sent into a receiver or galley, where they are made up like lines of type matter; but, of course, with much greater facility than types, being all in one piece.

Before referring to the third operation, distributing, it is necessary to describe the matrix. This is a piece of brass 1 inch long, by inch wide. Its thickness is that of the letter or point to which it corresponds. The character it is to produce is punched on to the side, where there is a cavity, in which the letter is engraved in intaglio, so that the casting made from it will be in cameo-that is, in relief. At the upper end of each matrix are teeth, arranged in a peculiar order or number, according to the character. That is, a matrix bearing any particular letter differs as to the arrangement of its teeth from a matrix of any other letter.

These teeth are relied on as the means for effecting the distribution or reassembling of the matrices. Above the open upper ends of the magazine channels is fixed a bar which has longitudinal ribs on its lower edge. These ribs are adapted to engage the teeth of the matrices, and to hold them in suspension. The ribs of the distributing bar vary in conformation at different points in its length, there being a special arrangement over the mouth of each channel of the magazine.

The matrices to be distributed are simply pushed forward horizontally upon the bar, so as to hang from it. Each matrix is thus suspended until it arrives over its proper channel, and on reaching this point the arrangement of the bar and the teeth permit the matrix to become disengaged, when it falls directly into the channel. Other matrices are meanwhile continuing their course along the bar to their proper points of disengagement. Thus the distribution is done entirely mechanically and automatically.

One of the advantages of thus using matrices instead of type can, perhaps, only be fully appreciated by those who are practically acquainted with the operation of type-setting. The lines of a column or a page must all, except those which begin and end paragraphs, be of a uniform length-not of irregular lengths like the lines of a page of type-writing. When the compositor finds that a line is short, and he cannot break a word because the recognised rules bearing on the division of words do not permit it, he has to insert extra or additional space between the words, in order to spread out the matter to the prescribed length. It is impossible beforehand to calculate the space that will be occupied in any line by a certain number of words, because the letters of which they are formed vary so much in width. Spacing out the matter to form a full line is called justifying, and the necessity for doing it greatly retards the hand compositor. In the Linotype machine 'space bars are used, which consist of two steel wedges, which slide upon each other, the planes of the outer edges being always parallel. These are inserted between the matrices of each word as set up, and when pushed up spread out the words, making the line of the required measure.

The Linotype machine produces letterpress printing surfaces much more expeditiously and economically than they can be produced by hand composition, or even by type-setting machines. Ordinary operators attain a speed of 8,000 to 10,000 letters per hour, whereas the hand compositor averages about 1,500 per hour. This increased product is attributable, first, to the greater speed at which matrices, as compared with types, can be operated on; and, secondly, to the possibility of performing automatically in one machine the two subsidiary operations of justifying and distributing which together amount to at least 33 per cent. of the work of the compositor. The machine also effects a great saving upon the cost of a printing office, as type, cases, and other appurtenances are unnecessary.

5. Memorandum on the British Association Screw Gauge for small Screws. By R. E. CROMPTON, M.Inst.C.E., Pres. Inst. E.E.

As a result of the two reports presented by the committee appointed by the British Association to design a standard screw gauge for small screws, a large number of users, including H.M. Post Office, have adopted them. In 1890 the London Chamber of Commerce appointed a committee to forward the question of making the British Association screw gauge universal among electrical manufac turers, and a circular was sent round to the entire electrical manufacturing trade, with the result that with hardly any exceptions the whole trade promised to adopt the screws, and thus ensure the extremely desirable result of making all the small screws used in electrical apparatus interchangeable. It is, however, much to be regretted that a considerable number of users of small screws (the principal offenders having their works in Birmingham) are still using other gauges, and thus complete uniformity has not been obtained up to the present time. One great difficulty in this matter has been that of obtaining standard gauges which could be referred to in specifications or orders for such screws. Wherever it is desired that the screws should be thoroughly interchangeable it is necessary in such specifications to have a paragraph somewhat as follows:

'Testing. Each box of screws will be tested as follows: A handful of one dozen screws will be selected at random from each box; these will be tested both as to the screw portion and the plain portion of the shank by being respectively screwed or pressed through the corresponding maximum and minimum gauge holes in the standard plates supplied on loạn with the order, and which must be returned with the finished screws. Any screw which cannot be screwed or pressed by hand into the maximum female gauge, or which can be screwed or pressed by hand without forcing into the minimum gauge, will be rejected. If more than one screw in each dozen thus tested is so rejected the whole box will be returned to the

contractors.'

Four years ago I found it necessary to have standard plates made for the purpose of ordering screws to the above specification. I had a number of such plates prepared, but found the very greatest difficulty in getting them made so that they would fulfil their required duty, the makers giving as an excuse that there was no standard B.A. gauge then existing to which they could refer. This difficulty can only be removed by a complete set of standards being made and deposited either with the Board of Trade or at the Society of Arts, or with a similar central institution; and it is highly desirable that the British Association should either call together the surviving members of the original committee or form a new committee to consider the question of making up these standard gauges and deciding on the place where they are to be deposited.

One question for the committee would be the requisite allowance of clearance between the absolute diameters of the various sizes as laid down in the report of the committee and the sizes of the maximum and minimum gauge holes in the gauge plates.

Another point of importance in order to make this standard screw gauge universal would be the issue of a short descriptive report, with illustrations, giving

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the sizes, clearances in gauge plates, best method of reproduction on English lathes of these screws, together with a few sectional drawings showing the shape of thread, rounding off, &c.

6. A Uniform Factor of Safety for Boilers and Machinery of Steamships By JOHN KEY.

The subject of this paper has arisen out of the fact that no uniform code of international regulations has yet been adopted by the various maritime countries and States for the general safety of machinery on board steamships, especially regarding the construction and strength of marine boilers and their connections.

A uniform factor or margin of safety might be devised on broad and intelligible grounds, without making any violent change, on the basis, not of the breaking strength, but of the elastic limit of the material-ascertained carefully by a uniform method of conducting tests that would be accepted by all civilised countries, in order that any steamship passed at one port for a properly certified working pressure might not, when new, be altered or reduced at another, similar in principle to the British system of measurements for ascertaining gross tonnage, and the regulations for preventing collisions at sea.

The following tabulated statement shows at a glance the working pressures for cylindrical shells of steel boilers allowed by the rules of the various authorities:-

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The water-pressure test allowed by the British Admiralty shall not exceed fourninths of the ultimate strength of the shell, and the working pressure is fixed at 90 lbs. below the test-pressure, which is called their 'constant margin' of safety for all pressures.

The Board of Trade allow a factor of safety 4.5, with additions according to the circumstances of each case.

Lloyd's Committee add inch, and the

British Corporation add inch to all thicknesses for wear, and their constants vary according to the form of riveted joint.

Hamburg rules allow a factor of safety 5.0, reduced to 47 when the longitudinal seams are drilled and double riveted.

Bureau Veritas allow a factor of safety of 4.4 after the plates have been corroded away by 0.04 of an inch.

These authorities all differ in their respective rules for diameter of shafts, thickness of plates forming flat surfaces, stress on stays, thickness of plain or corrugated furnace tubes, steam-pipes, and area of safety valves.

As an example of how unnecessarily we are hampered by want of uniformity even in boiler fittings and connections in the case of water-gauges, the English Board of Trade insist on having cocks or valves next the shell of the boiler, whereas the German Board of Trade will not have such a fitting; with the consequence that ships running to Hamburg are fitted with two standpipes, one with

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