unable to give particulars of the process of manufacturing cement in Belgium. He believed the method was kept very private, and he did not know whether the information was attainable. He had not been able to obtain it. He was glad to find that Mr. Wood had been so far able to solve the question of using slag successfully for agricultural purposes. Mr. Bell, both when Mr. Wood read his paper and when in Belgium, had stated that he could not obtain any results with it. Possibly Mr. Bell did not produce his slag in a condition fit for its application to the soil, or his land was not adapted for it. It would be very satisfactory to learn that there was a demand for slag in agricultural operations. That would be another means for getting rid of that vast accumulation which was now but waste. The PRESIDENT said that he had used slag both as a cement and as a concrete, and he had certainly never found anything equal to it. There were some very excellent cements, such as Portland and Blue Lias lime, but the slag cement surpassed anything of which he had ever had experience, as regarded cements made in this country. He believed that the Italians had adopted the same method of utilizing iron slag-perhaps in another form-for many years, and their cement had been noted as being most solid and rock-like. After it had once set it was almost impossible to remove it without blasting. He had no doubt that in the course of time cement made of slag would arrive at the same condition. As regarded the bricks, he had a very high opinion of them, because for building purposes they resisted the action of damp. The stock bricks and kiln bricks were very absorbent, and hence in our humid atmosphere, unless we built a hollow wall, we had a damp interior. He believed that slag bricks were almost like fire bricks; and if they could be obtained at anything like the price which had been mentioned they were a most valuable acquisition. They would only need to be introduced to find their way into the hands of all engineers and contractors. Such persons would appreciate their good qualities, and award to the inventors that meed of praise and that support to which they were so justly entitled. It was also a matter which was well worthy of the consideration of all persons engaged in building operations. The present discussion might be the means of more fully introducing the invention in this part of the country. There were many things in the north of which we in the metropolis knew very little. He was very glad that the subject had been introduced to the Society, and he hoped that benefit would result both to the inhabitants of the south of England and to the inventors of the slag brick, which was produced from a material which had been for many years without any value whatever. December 1st, 1873. JABEZ CHURCH, PRESIDENT, IN THE CHAIR. A NEW METHOD OF SETTING OUT THE SLOPES OF EARTHWORKS. By CHARLES JULIAN LIGHT. In the following brief paper the author desires to lay before the Society a method, which he believes to be new, of setting out the sidewidths of cuttings and embankments in sidelong ground. The conditions under which this operation has to be performed may be divided generally into three classes. 1. When the cross-section is practically level, say with an inclination of surface less than 1 in 100. 2. When the inclination of surface in cross-section is fairly uniform and exceeds 1 in 100. 3. When the cross-section is irregular and rough. In cases of the first class, of course the process is perfectly simple, and in those of the third there is no better method than by taking cross-sections as often as required, plotting them and setting out the centre and slopes first upon paper. It is only with the second class therefore that the author proposes to deal. This is, however, a very large class, and probably includes more cases than both the others together, especially at the present day, when the use of sharper curves and steeper gradients leads to the practice of contouring round the shoulders of hills rather than cutting through their summits. The ordinary process may be described as tentative, the result being attained by a succession of approximations, the number of which, and, consequently, the speed of the operation, depend entirely upon the skill and experience of the engineer in charge. The operation itself is briefly as follows: Let the work to be set out be a railway cutting, through which the chain pegs of the centre line have been previously fixed and their levels taken. The engineer proceeds to measure horizontally from his centre peg, and at right angles to the centre line, a distance up the hill side such as his judgment leads him to expect will bring him to about the top of the slope at that point. Here he takes a level, and, adding the difference between it and that at the centre peg to the sectional height at that point, he calculates therefrom the horizontal distance at which the slope would run out. This will, in all probability, not agree with the horizontal distance measured; he therefore takes another distance and a corresponding level, endeavouring to be, this time, rather beyond the true distance than not, if the first time he were short of it, or vice versa, so that the true point, if not actually hit upon, may lie between his trial points. So he proceeds, with more or fewer trials according to his skill, until the exact point is found at which the top of the slope, as calculated from the height, coincides with the surface of the ground at the distance measured. The operation has then to be repeated for the lower side, and for each point at which side widths are required. For this process of approximations the author aims at substituting a practically exact measurement along the surface of the ground, based upon data easily obtained, and deduced from tables of a simple form. The formula employed and the mode of arriving at it will be readily understood with the aid of the accompanying diagram, No. 1: F being formation width from centre line, F' formation measured on ground, S slope of cutting or embankment, D difference of level on cross-section at a distance A from Substituting this value of y in the first equation we have The diagrams (see Figs. 1, 2, 3, and 4) have been drawn for cuttings, but it is obvious that the same formula applies to embankments, the + sign in the denominator applying to the lower side in cuttings and the upper in embankments, and the sign to the upper side in cuttings and the lower in embankments. The above formula includes all cases except those in which H is small, and is approaching the balance line. When H' O, or the formation width itself cuts out at the surface on the lower side in cuttings and the upper in embankments, as in diagram No. 2: H = F D M and F=H D |