Calibration of Instruments used in Engineering Laboratories.-Report of a Committee, consisting of Professor A. B. W. KENNEDY, F.R.S. (Chairman), Professor J. A. EWING, F.R.S., Professor D. S. CAPPER, Professor T. H. BEARE, and Professor W. C. UNWIN, F.R.S. (Secretary). (Drawn up by the Secretary.)

AT the first meeting of the Committee it was decided to investigate initially the accuracy of instruments for measuring the tension coefficient of elasticity, or Young's Modulus. A general letter was addressed to various professors and others in charge of engineering laboratories inviting co-operation. Most of those written to agreed to make a series of measurements for discussion by the Committee.

It was then decided that sets of standard test bars should be prepared, to be subjected to tension and measurement. Figs. 1, 2 show the forms of test bar decided upon. Two of the standard bars of each set are cylindrical bars, with screwed ends of about 1-inch and 3-inch diameter. These have gauge points for measuring instruments, suitable for extensometers of 8-inch, 10-inch, 16-inch, or 20-inch range. These bars are of a special steel of high tenacity, rolled specially for the Committee by the Blaenavon Company. The whole of the bars were cut from a single rolled bar about 20 feet in length, and were very accurately turned to the required dimensions by Mr. W. R. Munro. The third bar of each set was a flat bar, of section about 2 inches by inch, of mild steel. All these bars were cut from a single plate, and they were prepared with gauge points at 8 inches and 10 inches.

In order to obtain some preliminary information as to the mechanical properties of the standard bars, one round bar and one flat bar were tested in the testing machine at the Central Technical College. following table gives the results obtained :

Preliminary Tests of Materials used for Standard Bars.

The

The Committee then drew up a test-sheet form to be issued with the bars, on which measurements were to be recorded. These sheets were so arranged that two sets of measurements for each bar, and the mean of these, should be recorded; also that the extensions for short and long ranges of stress should be recorded. It was hoped that in this way some measure of instrumental errors would be obtained.

In January two sets of bars were sent out for measurement, to be circulated amongst those who had consented to co operate with the 1895.

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Committee. The measurements have taken much time, and the whole of the reports of observers have not yet been received. Some of those already sent reached the Committee too late for discussion this year. It appears, therefore, to the Committee that it is unavoidable that only an interim report can be presented this year. The Committee ask for reappointment, in order that the results obtained may be discussed and presented.

It may, however, be useful even at this stage, to give a very short summary of some of the results sent in. The following table gives a summary of the measurements of the standard bars by different observers. It will be seen that there is an appreciable difference even in the measurement of the dimensions of the same bar. The flat bar, it may be noted, was machined on the edges only.

The following table gives the values of the coefficient of elasticity for the greatest range of stress observed for each bar. The values are given for the first and second loading of the bar, and also the mean of the two observations. It will be seen that, even for the mean of two sets of readings, over the greatest range of stress the elasticity of the bar permits, there are very appreciable differences in the values obtained. It remains to be considered in a more detailed discussion of the results whether any evidence can be found as to the source of the discrepancies. It may be due to error of the testing machine, to error of magnification by the extensometer, or to error of calibration of the extensometer. It is just possible it may be due in part to temperature or other action independent of both testing machine and extensometer.

General Values of E obtained for the greatest range of stress the bar

An Ancient Kitchen Midden at Hastings, and a Barrow at the Wildernesse.-Report of the Committee, consisting of Sir JOHN EVANS (Chairman), Mr. W. J. LEWIS ABBOTT (Secretary), Professor J. PRESTWICH, Mr. CUTHBERT PEEK, and Mr. ARTHUR J. EVANS. (Drawn up by the Secretary.)

The Hastings Kitchen Middens.

THE cliffs at Hastings are formed of sandstones belonging to the Ashdown Sands, which at Castle Hill rise some 180 feet in height. These are very much fissured, and often a centre block becomes keyed above, while it breaks away below, thus forming a veritable cave. Along both the east and west cliffs these natural fissures have been widened out artificially, and doubtless have served as human habitations in the past.

Upon the tops of some of these fissures, and upon the rock-ledges on the face of the cliffs, there are large accumulations of materials of various

kinds, the upper part of which is a subaerial deposit, which varies in thickness from an inch or two up to four feet. Below this is the midden material, composed of all sorts of the waste products of life. It is usually only a few inches in thickness, but occasionally it is eighteen inches thick. It is much darker than the adjacent material, owing to the large quantity of charcoal and other carbonaceous matter contained in it. Frequently there are hearths which occur on old surfaces, where the material has been burnt to a red-brick mass, extending downwards from half an inch to three inches; in wet weather this is very friable and rotten. In places there are seams of shells: the most extensive layers consist of those of mussels and oysters, which are in the worst state of preservation. Limpets are almost as plentiful, but better preserved than the former. Winkles are very abundant, and always of very large size. Buccinum undatum is fairly plentiful, but Trophon is absent. Cardium echinatum is frequently found, but no trace of C. edule has been observed. The occurrence of Purpura lapillus is curious. Some pieces of bone have recently been discovered stained of a purple colour, which would suggest a knowledge of the dye furnished by this species. Pecten opercularis, Natica, and Mactra also occurred, while in one place a heap of snail-shells of a very large size was found these are probably Helix aspersa, but the shells are larger and more globose than those of the existing species, and the light-brown bands of colour that are left make the species to resemble H. pomatia. There is also a large quantity of fish-bones distributed through the material, some of which bear traces of roasting: they include skate, gurnard, cod, whiting, mackerel, sole, turbot, and plaice. Large quantities of other bones formed part of the material; they are always detached, and bones are never found together in the natural position; frequently they show the action of fire, and all the marrow-bones are split. In two cases a split bone was discovered with a flint wedge still in situ. The bones include those of frog, ducks, some species of gull, red and black grouse, and other species of birds not yet determined; rabbit, pig, horse, sheep, goat, red deer, roe, ox, badger, fox, wolf, dog.

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Fragments of pottery abound occasionally; it is possible to restore about a third part of a vessel, from which its nature and shape can be determined. They are all of domestic patterns (not burial), flat-bottomed, and they usually have a deposit of soot upon them. Some appear to be very coarse and sun-dried, but the majority are well-baked and hand-made. They vary in colour from a discoloured dirty red to black, the latter predominating. They are, on the average, of good neolithic quality.

Large quantities of flint boulders appear to have been taken up for implement-making. All the implements are small; no axe or war implement has been discovered. Many hundreds of flakes show signs of wear, and these sometimes reach five inches in length. Round and hollow scrapers abound, from a very large size down to needle-makers, as do all kinds of drills. None of the arrow or lance heads are barbed, but they are often very symmetrically worked to a lanceolate shape. The commonest form is a nicely worked lanceolate-shaped flake, single or double ridged, generally the latter, with a well-formed butt, with or without secondary work on the edges. The butt ends of hundreds of these have been found, the points excessively rarely. There is, however, a still more interesting group of implements than any of the foregoing, owing to their diminutive size, their peculiar outlines, and delicate workimplements in every way similar to those which have been found in