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 manufacturers, 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 loan 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

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::-

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

cocks and one without, to which our English Board of Trade has to shut its eyes, as the German standpipe, from their point of view, is unsafe and ought not to be allowed.

7. Experiments on the Transfer of Heat through Plates with Variously Arranged Surfaces. By WILLIAM GEORGE WALKER, M.Inst.M.E., A.M.Inst.C.E.

The object of these experiments is to compare the effects on the transfer of heat of variously arranged surfaces projecting from the primary surface of a plate in contact with steam, air or water.

Two cylindrical smooth vessels were constructed of exactly similar dimensions, cut from the same brass tube, 63 inches in length and 2 inches in diameter, fitted with water-tight lids, through which thermometers were inserted. When filled with water no difference was found to exist between their respective powers to absorb or discharge heat. One of the cylindrical vessels was then fitted with copper ribs 5 inches long, inch wide, 012 inch thick, soldered on longitudinally. The ribs were spaced equally round the cylinder and tried as follows:

The heating of the two cylinders was performed by suspending them in steam from boiling water. The two cylinders to be compared were filled with water, and placed in steam when their temperatures were 65° Fahr.

The reading of the thermometers, together with the time, was noted simultaneously at every 10 degrees. The time was taken in seconds by a ship's chronometer. When the thermometers became stationary at 210° Fahr. the cylinders were suspended either in air or water and allowed to cool down, the temperatures being noted every 10° Fahr. and the time in seconds.

The difference between the temperatures of the corresponding plain and ribbed cylinders increased from zero and reached a maximum, after a certain time after which they again closed to equal degrees.

The ribbed surfaces increased to a considerable extent the rapidity of transfer of heat either when absorbing heat from steam or discharging it into the air. The effect was not so great when cooled in water. In the externally ribbed cylinder the greatest advance in temperature over the corresponding plain one was 18° Fahr., 33° Fahr., 8° Fahr., when in contact with steam, air, and water respectively. The addition of the internal ribs to the external ones did not produce much effect. With the internal ribs alone, the rapidity of transfer of heat was increased when cooled in water, but practically no effect was perceived when in steam or air.

The external ribs were more effectual in discharging heat to the atmosphere than in absorbing it from steam. This difference may be due to the condensed layer of water which was deposited on the surface.

Coiling wire round was also tried. The temperature of the coiled cylinder fell faster than the corresponding plain one in air, but rose slower in steam-due probably to the condensed layer of water deposited between the wire coils. No difference was noticed when cooled in water. The comparison of rough and smooth surfaces when absorbing heat from steam or discharging it into air or water was also tried.

8. A New Principle of Aerial Navigation. By Lieut. B. BADEN-POWELL.

It has been the constant desire of inventors to devise some means by which we may be able to navigate the atmosphere. Wings, vertical screws, aeroplanes, have all had their advocates, and great hopes were aroused in the balloon. Many proposals were made for steering this aerial buoy, and sails and rudders were applied to the apparatus, until scientists pointed out that these could be of no avail

on any apparatus which floated in, and with, one medium. Yet it is this very principle which I wish to advocate, and to state broadly a method by which I believe we might sail through the air, which depends upon three well-established facts. First, a kite retained by a string will ascend when a wind is pressing on its under surface, and will raise a considerable weight. Secondly, in the absence of wind, the same effect may be produced by drawing along the kite through still air. I have myself been lifted by a large kite under such circumstances. Thirdly, by balloon ascents, observations on clouds, mountain records, and especially observations on high places as the Eiffel Tower, it has been found that the wind almost invariably increases in velocity the higher we get, so that the currents of air 1,000 feet up move about three times as fast as those below. It follows from these principles, that if two kites connected by a long string, so arranged that one floats in a current of air blowing at a different rate (or different direction) from that in which the other floats, there will be a reciprocal action, the kite in the lower medium being supported by being drawn along by the kite in the higher stratum, which in its turn is kept aloft by being retarded by the other.

A kite of 1,000 square feet area is capable of supporting a man in a breeze of 10 miles an hour, or when being towed at that rate through calm air. If the wind near the surface of the earth be blowing at this rate (rather below the average), it will usually be travelling at 30 miles per hour at an elevation of 1,000 feet.

With two such kites connected together by a long rope, with a car attached to the rope near the lower kite, if the lower one be drawn along 10 miles an hour faster than the wind, it will support a man, and travel at a rate of 20 miles an hour. But if the upper kite travel at this rate it will be retarded to an extent of 10 miles an hour, and hence the whole apparatus will float along with the wind. In this way we might make a light apparatus for navigating the air. The extent to which it might be steered out of the wind's course, practice alone can determine, but even if this be not much, we still should have an air-ship possessing very many advantages over a balloon, and to which propelling agents could be much more easily applied.

9. Receiver and Condenser Drop. By Professor A. E. ELLIOTT.

REPORT-1895.

SECTION H.-ANTHROPOLOGY.

PRESIDENT OF THE SECTION.-Professor W. M. FLINDERS PETRIE, D.C.L., L.L.D.

THURSDAY, SEPTEMBER 12.

The PRESIDENT delivered the following Address :—

IN a subject as yet so unmapped as anthropology there is more room for considering different points of view than in a thoroughly organised and limited science. The future structure of this science depends largely on the apprehension of the many different modes of treating it. The time has not yet come when it can be handled as a whole, and therefore at present we may frankly consider various questions from an individual standpoint, without in the least implying that other considerations should not be taken into account. It is only by the free statement, however onesided, of the various separate views of the many subjects involved in such a science, that any comprehensive scheme of its organisation can ever be built up. In remarking, therefore, on some branches at present I shall not attempt a judicial impersonality, but rather try to express some views which have not yet been brought into ordinary currency.

Elaborate definitions of anthropology have been formulated, but such are only too liable to require constant revision as fresh fields of research are added to the domain. In any new country it is far safer to define its limits than to describe all that it includes; and all that can yet be safely done in anthropology is to lay down the sphere of influence,' and having secured the boundaries, then develop the resources at leisure. The principal bordering subjects are zoology, metaphysics, economics, literature, and history. So far as these refer to other species, as well as to man, or to individuals rather than to the whole race, they stand apart as subjects; but their relation to the human species as such is essentially a part of anthropology. We must be prepared, therefore, to take anthropology more as the study of man in relation to various and often independent subjects, than as an organic and self-contained science. Human nature is greater than all formula; and we may as soon hope to compact its study into a logical structure, as to construct an algebraical equation for predicting its course of thought.

Two of the commonest and most delightfully elastic words in the subject may be looked at once more-'race' and 'civilisation.' The definition of the nature of race is the most requisite element for any clear ideas about man. conception of the word has been modified recently more than may be supposed by Our present our realising the antiquity of the species. When only a few thousand years had to be dealt with nothing seemed easier or more satisfactory than to map out races on the assumption that so many million people were descended from one ancestor and so many from another. Mixed races were glibly separated from pure races,