128 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[April, 



a child. Seats intended exclusively for children may be twenty-four inches 

 from back to front. 



18. Galleries. — None can be permitted in any part of the chancel. Where 

 necessary, they should not enclose the columns against which they rest, so 

 as to break the upright lines of the shafts from the floor to the roof. Where- 

 ever placed, they should, as much as possible, be made to appear as adjuncts 

 and appendages to the architectural design of the interior, rather than as 

 essential parts or features of it. The Socipty will not sanction any plan 

 involving the erection of a gallery, unless in cases where it is distinctly shown 

 that no room is unnecessarily sacrificed, by inconvenient arrangements, on 

 the floor. 



19. Vestry. — The vestry should have access to it from without. 



20. Finishings. — Wall wainscoting, or wood linings to walls, to be avoided 

 wherever convenient. Wood linings to walls confine the damp, and fre- 

 quently occasion dry rot. For the same reason cement skirtings are to be 

 preferred to wood, particularly on the ground floor. Where the linings to 

 the walls are I f wood, holes should be perforated under the seats to allow 

 the circulation of air. As it is scarcely possible to prevent rot if any wood 

 is in contact with the w alls, the ends of seats next the walls should be omitted, 

 anil cement, painted, be substituted. 



21. Excusable and Customable Articles. — Architects are particularly desired 

 to take care that an accurate account be kept of the quantities of customable 

 and exeiseable articles used, where the expense of enlarging or building a 

 church or chapel will amount to £500 or upwards, such as may be duly cer- 

 tified or verified by affidavit. 



MR. VIGNOLES' LECTURES ON CIVIL ENGINEERING, AT THE 

 LONDON UNIVERSITY COLLEGE. 



SECOND COURSE. — LECTURE XVII, AND LAST \ FOR WHICH lit ARE IN!i 

 TO THE "MINING JOURNAL." 



Before proceeding to a summary of the second course, Mr. Vignoles ob- 

 served, that there was a material point connected with the subject which had 

 not been sufficiently discussed — viz, the motive power to be employed ; on 

 this greatly depended the principles on which a line of railway should be 

 laid out, the end and object being to convey the greatest extent of traffic at 

 the least cost : this cost was compounded — first, of the interest of the capital 

 expended, which should be considered a constant charge ; and second, of the 

 periodical working expenses — the work to be done being summed up in the 

 general expression of "overcoming all obstacles to facility of motion.'' 

 What are these obstacles? They might be divided into two great heads — 

 Gravity and Friction. 1st. Gravity is a natural cause existing under all cir- 

 cumstances, and. affecting lines deviating from the horizontal, in direct pro- 

 portion to the sine of the angle of inclination. Engineers, therefore, have 

 considered that the first principle in laying out roads, should be (under 

 limits) to approximate as nearly as possible to the horizontal, in order to ex- 

 clude one of ihe great causes of obstacle ; since, with maximum loads, the 

 retardation arising from gravity is most felt. When such could not be 

 effected, then to distribute the total rise (or effect of gravity) along the easiest 

 ratio of slope. But, in practice, the occurrence of maximum loads, in ordi- 

 nary passengers and merchandise traffic, forms the exception, instead of con- 

 stituting the rule, and it is only when a regular and constant heavy trade is 

 to be anticipated that horizontal communications should be insisted on. 

 2nd. Friction, is a physical cause, varying according to the perfection of the 

 road and of the vehicles moving on it. In the practical working of a railway, 

 however, so many expenses arise under the heads of " conducting traffic, 

 management, &c." common to most.lines, whatever the gradient, that they 

 tend to make the cost of overcoming friction and even gravity (particularly 

 with the ordinary light loads) but a small fraction of the total charges. 

 Comparing the amount of obstacles on a railway with that on the ordinary 

 road (where the friction, meaning thereby axletree friction and surface re- 

 sistance, may be called sixteen to twenty times greater than on a railway), 

 and assuming the inclination on railway and road to be the same, the genera] 

 result is that the perfection of the railway surface moved over, and the im- 

 provement of carriages, or rather that of their wheels and axles, cause the 

 effect of gravity to be felt in the most sensible degree on railways ; while the 

 imperfection of the road causes it to be comparatively scarcely appreciated 

 Hence with the wretched surfaces of the old roads, and the clumsy wheels of 

 our primitive vehicles, the hills seem to have scarcely added to the obstacles 

 to be overcome. As the road surfaces and carnages improved, and increased 

 speed and heavier loads were introduced, the necessity for the greater per- 

 fection of the ordinary road became apparent, and the remedy was applied 

 in various degrees during the last 100 years until it was completed as far as 

 possible, in the extensive improvements by Telford and Macneill on our great 

 highways. But in carrying out this principle on railways we have run into 



the opposite extreme. We should first take in one sum the retarding causes 

 of gravity and friction — viz., the friction, being constant, or nearly so. 

 putting aside the resistance of the air at high velocities, varying only in the 

 perfection of the wheel axles, and in the mode of lubricating. (Ihe surface 

 resistance on railways being, practically speaking, nothing), and the maxi- 

 mum gradient, or lather the gravity due to it : — their sum will be the con- 

 stant divisor for the motive-power, of whatever description that motive 

 power miglr be ; and. in considering the latter point, it must be the distri- 

 bution of the traffic, or what may be called the average hourly load through- 

 out the year which is to determine the question. In many instances, in this 

 point of view, it would probably often be found most economical to use ani- 

 mal power, (as is done on the Edinburgh and Dalkeith Railway), were not 

 velocity required — which, on railways, enters so materially into the calcu- 

 lation, that mechanical power in some shape becomes necessary ; and this 

 divides itself into stationary power, or when the mechanical means are fixed, 

 and locomotive power, or when the machine travels along with the load. 

 There are two serious difficulties connected with the latter system ; — first, a 

 great addition to the load, equivalent on the average to doubling it ; and 

 next, that the fulcrum through which the motive power must be transmitted 

 — that is, the rail on which the locomotive driving wheel impinges — is greatly 

 affected by atmospheric causes, occasioning great variation in the adhesion, 

 and consequent uncertainty from slipping of the wheel, so that, as explained 

 in a former lecture, the load after a locomotive engine is really limited by its 

 adhesive power, and not. as might at first he suppused, either by the cylinder 

 power or boiler power. Considered abstractedly, stationary power is cheaper, 

 and always would be so if the traffic were certain and regular, with maximum 

 loads and very moderate speed, even with the present obstacles of ropes, 

 sheaves, and all their contingent complicated apparatus ; but at high speed, 

 with a great length of rope, the experience of the working of the Blackwall 

 Railway has shown that for passenger trains only, there was, compared with 

 the most expensively worked lines on the locomotive system, to say the least, 

 no economy in the motive power, though other conveniences arising from the 

 peculiar arrangements on that line. were, perhaps, in this special case, more 

 than an equivalent. A most serious obstacle to stationary power, was the 

 necessity of absolutely stopping, and disengaging and refixing, the trains at 

 each station, which stations could not be conveniently, and certainly not 

 economically, placed further apart than three or five miles, for it could 

 readily be proved, than on a continued distance of six or seven miles of rail- 

 way worked by a rope, the power of the largest engine that could well be 

 erected, would be absorbed in moving the rope only. The Professor then 

 went largely inlo a consideration of applying stationary engines as the 

 motive power in working inclined planes under a variety of circumstances, 

 and recommended to the students to consult the valuable work of Mr. Nicho- 

 las Wood on this subject, and indeed on all the details of railway working, 

 of which, particularly in the third edition, there was m<>st of the latest in- 

 formation. In many situations, however, where water power could be ob- 

 tained, the stationary rope and pulley system might be advantageously intro- 

 duced. Gravity became the motive power, on what were called self-acting 

 inclined planes ; that is, when the gravity of a descending train of laden 

 carriages brought up a train of others empty or partially laden; or where 

 skeleton wagons, or water tanks on wheels, could be used as artificial coun- 

 terbalancing weights in either direction alternately ; the circumstances under 

 which self-acting inclined planes could be properly introduced were rare. 

 Mr. Vignoles then gave a clear account of various modes of working self- 

 acting inclined planes ; among these was described a curious and interesting 

 one near the great limestone quarries in North Staffordshire ; another on the 

 St. Helen's and Runcorn Gap Railway, which lie had himself put up. and 

 also the planes for the Great Portage Railway, across the Alleghany Moun- 

 tains, in the United States of America. Stationary power might also be used 

 to a greater extent on the atmospheric system, whereby, to speak metaphori- 

 cally, a rope of air was substituted for a rope of hemp or wire, and where no 

 pullies were required, nor any necessary stoppage at the intermediate en- 

 gines, where only the carriages had to be moved, and where nearly the whole 

 dynamic force generated was made available for motive power. This system 

 had already been explained to the class, and practically illustrated on a rail- 

 way thus worked, and need not be further alluded to. The Professor was 

 preparing for publication a separate lecture " On the Atmospheric Railway 

 System," to be illustrated with plates, and tables, and appendices, in which 

 that interesting subject would be fully gone into, and all the mathematical 

 and philosophical investigations given, with estimates of the cost of such 

 railways under various circumstances of traffic and gradient ; fully enabling 

 the value of the principle, as a motive power, to be appreciated. Although 

 modern practice had almost discarded the use of animal power from railways, 

 it might be proper to refer cursorily to it. A horse seems adapted to drag 

 vehicles, from the mode in which he adjusts his muscular action, so as to 

 throw the greatest effect on the line of draft ; in making an effort to draw a 

 carriage, the body of the animal is bent forward, throwing upon the latter 

 the part of its weight necessary to overcome the resistance, the muscular 

 force of the legs being employed in keeping up his traction and moving the 



