1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



245 



RUNNING GUAGE, 



FOR measuri:-:g the width of the rails of a railwat. 



This apparatus is, as it were, a skeleton hand truck, consisting of 

 a pair of small wheels and axles, and a handle to drive them. 



The wheels A B are grooved after the manner of pulleys, so that 

 they rest on a narrow or wide rail without shaking; they are fixed ou 

 the axles C D, and are therefore without shake ; the axles turn in 

 bearings; one of the axles D has a shoulder and pin at its end E, and 

 a washer between the pin and the bearing allows the axle to revolve 

 freely, and yet have no shake endwise. The other axle C moves 

 freely on its bearings endwise ; it has a long shoulder at its end, on 

 which is fitted a brass tube F, and a pin and a washer keep it in its 

 place ; the tube has a projecting pin, which passes tlirough a long hole 

 in a piece of iron or brass G, fixed to the framework of the instrument ; 

 the pin projects far enough to enter the short end of a light wooden 

 lever or index H, the long end of which points to a graduated arc I. 

 As the instrument is pusliod along, the free axle C slips in and out as 

 the wheel A follows the irregularity of the rail, and by the connexion 

 of the axle with the index, the index points out the width of the rail 

 on the graduated aix. 



Where a rapid examination of the rails is required, the guage may 

 be hooked to the tender, and the man who watches the motion of the 

 index, may throw on the road any distinctive material, such as oyster 

 shells, broken green glass, red brick or tile, broken earth-ware, chalk, 

 or wooden cubes ; so that the workmen will find the places marked 

 which they are to repair. A. C. 



CURVES ON RAILWAYS. 



Sir — In the last number of your journal, a correspondent ("Sur- 

 veyor") has given a method of setting out circular arcs for railway 

 purposes by means of ordinates measured from and at right angles to 

 the tangent lines, and as from his communication it does not appear 

 clear that he recommends it from his own personal experience in its 

 application, it may not be unacceptable to you to be assured by one 

 who has practised it with success, that the method is good and suit- 

 able for almost every variety of surface, occasionally modifying it as 

 any peculiar circumstances arise ; it is best suited for setting out 

 curves upon the surface jirior to any practical operations being com- 

 menced, for in deep cuttings or on high embankments considerable 

 difficulties present themselves to this method, and therefore recourse 

 should be had to other means. One great recommendation to the 

 method of ordinates is, that any error committed in one ordinate is 

 extended no further, and such error may be instantly detected and 

 corrected by the eye, by setting up (perpendicularly) a boring rod 

 about 10 feet long at the extremity of each measured ordinate ; when 

 eight or ten of these rods are set up, the observer, upon looking along 

 them, will perceive any irregularity in the curve, even to one cpiarter of 

 an inch. 



I have long since computed a set of tables of ordinates to a variety 



of radii, and about two years ago was preparing them, together with 

 other methods of setting out curves, and also some useful tables in my 

 possession, for publication, for which purpose I then had the necessary 

 eno^ravings made ; business, however, has caused me to defer it from 

 time to time, but I am now making such arrangements for that purpose 

 that I hope shortly to be able to accomplish it. 



I am. Sir, 

 2, West Square, Your obedient servant, 



June 15/A, 1839. F. W. Sim.ms, C.E. 



WELL SINKING. 



The accompanying drawing is a section of a well sunk at the foot of 

 the reservoir in "the Hampstead Road for the New River Company. 

 It also exhibits the strata of the ground passed through. The follow- 

 ing account is an abstract of a paper " On the supply of water from 

 Artesian Wells," by R. W. Mylne, Esq., read liefore tlie Institution of 

 Civil Engineers, April 30, 1839, fully describing the nature of the 

 works. 



Artesian wells, so called from their having been originally adopted 

 in the province of Artois, by the Romans called Artesium, are usually 

 made by boring vertically through a deep stratum of clay into one of 

 sand, which generally contains water. The water will rise to a con- 

 siderable height, depending on the elevation of the point at which the 

 sand stratum drops oui from under the bed of clay. Tlie London basin 

 is peculiarly adapted tor these wells, as on the large bo« 1 of chalk is 

 a thick lining of sand, supporting a deep bed of clay, known as the 

 London blue clay. On boring into this sand, or into the chalk, the 

 water rises to various heights, and it has been thought that an abun- 

 dant supply for the metropolis might thus be obtained. With the 

 view of ascertaining what dependance can be placed on this source, 

 the New River Company sunk a well, the details of which form the 

 subject of this commimication. Before entering on these the author 

 mentions several instances of wells supplied from the sand spn'iigis in 

 various parts of the metropolis, and other parts of the country. In 

 most of these the supply has been so att'ected by neighbouring wells, 

 or the upper ground and buildings have been so endangered by the 

 large cavities produced in consequence of the fine sand being pumped 

 away, that the wells have been abandoned. Several remarkable in- 

 stances of the ertects of this subsidence are detailed in this communi- 

 cation. Experience thus appearing to shew that little dejjendance 

 can be placed on the sand springs, it has been suggested to sink 

 through into the chalk ; but the supply from this source also is atfected 

 in a remarkable manner in various cases. 



The author then proceeds to give the particulars of the sinking of 

 the well in the Hampstead Road. In March, 1835, an excavation, 20 

 feet in diameter, and 23 feet deep, was made : the sides were sup- 

 ' ported bv wooden curbs with puddle at the back, so as to shut out the 

 land springs. At the bottom of the curbs, just in the blue clay, a cast- 

 iron footing was adiled, and a brick shaft of 12 feet G inches diameter 

 carried up to the surface of the ground. The excavation was con- 

 tinued for 59 feet through the clay, steined with 9 inch brickwork in 

 cement, iron rings were placed at every 8 feet of the brickwork, and 

 of a greater diameter than the shaft, and projecting into the clay a few 

 inches so as to support the shaft in its progress; the brickwork was 

 continued through 57 feet only, leaving 2 feet of clay for a foimdatioii. 

 The excavation w>is now reduced t(j 10 feet 9 inches, for the purpose 

 of introducing cast-iron cylinders formed of six segments, (i feet in 

 length, united by bolts through fianches on the inside, and leaving 9 

 feet 9 inches clear diameter. These being joined together were forced 

 down by hand screws, as the sinking continued tln-ough the 2 feet of 

 blue clay and through 10 feet of soft mottled clay, at the bottom of 

 which water appeared. 



The well was kept dry by an engine and two 8 inch pumps in two 

 lifts, and the sinking continued for 8 feet, through a bed of fine brown 

 sand. Cavities were now discovered behind the cylinders, w hich were 

 forced out of the perpendicular by the unequal pressure, and became 

 completed jambed. A second set of cylinders was now prepared, and 

 the sinking continued for 26 feet through the remainder of the dark 

 brown sand, soft mottled clay, a thin layer of pebbles and lilack sand 

 closely embedded, and 4 feet tj inches of dark brown sand. Cavities 

 were again formed at the back, and the cylinders again became jandjed. 

 A third set of cylinders was now prepared of 7 feet 4 inches diame- 

 ter, and the sinking continued through 7 feet of dark brown sand, and 

 5 feet of dark quick sand, when they again became jambed. During 

 the latter portion of the work great difficulty was experienced from 

 the blowing of the sand often to the height of 6 feet ; tliis occasioned 

 great cavities behind the cylinders and the brickwork ; several seg- 

 ments of the former were broken at their vertical flanches, and the 

 lower part of the latter was much cracked. A large cavity also was 



