TRANSACTIONS OF THE SECTIONS. 231 
of electric contact-making and breaking apparatus, acting through a simple electro- 
magnetic contrivance which in turn operates upon and deflects a pen, style, or 
marker, which records upon the strip of accurately divided paper the whole of the 
moyements in question. In lile manner, the directions sent and received for regu- 
lating the traffic are recorded, ag also is the passing of trains, which are distin- 
guished the one from the other; and the whole of these movements are timed, and 
the time is recorded uniformly on one edge of each of the strips of paper, 
Between the time-records on the one edge of the roll or strip and the passage of 
trains recorded, say, on the opposite edge, the directions sent and received and 
the movements of the various signal- and point-levers, or the movements of the 
parts of the interlocking gear, are recorded between the records on the two edges of 
the strip, and in a clear and intelligible manner ; and on reference to these rolls all 
questions connected with the traflic-working can be solved with perfect certainty ; 
and upon the rolls or strips of record-rolls being removed and sent to the manager's 
office, he can, at a glance, by comparing the various records, see the work done 
upon the various parts of the line during a given time; and they can be referred to 
at any time, and could be produced and could be received as reliable evidence in 
any legal or other tribunal. 
The apparatus costs only a small sum, and the annual cost of maintaining and 
working it is very small. 
On Improvements in the Mariner’s Compass. 
By Sir W, Tuomsoy, LL.D, FBS. 
On Power-Couplings for Rolling-Mills and other Machinery. 
By F. H, Varusy and Epw. Furnzss, 
In arresting a heavy body in motion it is necessary to exert a force equal to the 
dynamic effect of the weight of the body, multiplied by the square of its velocity. 
Should this be effected instantaneously, a great concussion is the result—such being 
the effect experienced when a piece of machinery in rapid rotation is suddenly 
arrested by clogging, causing the teeth of the wheels to be stripped off or the 
shafts broken or distorted, which frequently occurs with iron rolling-mills, sugar- 
cane crushing-mills, and not unfrequently causing the breaking of the screw-shafts 
of steam-vessels and all classes of machinery subject to rapidly varying strains. 
To reduce these enormous strains to within the working strength of the material 
of which the machinery is constructed, it is necessary to spread the force of the 
concussion over a portion of a revolution or revolutions, or period of times, and so 
destroy its intensity, Contrivances for effecting this purpose have hitherto taken 
the shape of friction-breaks or clutches. They, however, are open to the objection 
that they consume a large amount of useful power by generating heat and destroying 
the surface by abrasion. The authors describe a means of obtaining a better result 
by an hydraulic pressure, rendered elastic by placing in the fluid a number of 
elastic bodies, such pressure acting against the face of a ram working in a cylinder. 
To convert the longitudinal motion of the ram into the rotatory motion of the 
shaft they employ the following arrangement :—The wheel which communicates 
the power to the machinery is bored to fit freely on a shaft, and has a boss with 
its face on the inner side shaped of a spiral incline of screw form, and which is 
made to bear against an annular plunger, the outer end of which is shaped to the 
contrary screw form. The hole in the plunger is bored to the same size as the 
wheel, and works in a cylinder fitted concentrically on the shaft which passes 
through the hole of the ram and wheel, the ram being made watertight by suitable 
packing or leather. The outer end or mouth of the cylinder has slots or recesses 
cut into it longitudinally in which lugs or projections on the ram work, so that 
the ram can slide in and out the cylinder, but cannot turn unless the cylinder 
turns with it, proper inlets for charging the cylinder with fluid and elastic balls 
being provided. If the shaft be revolving, and the wheel driving the machinery is 
stopped, the ram is immediately pressed into the cylinder and compresses the 
