128 REPORT—1849. 
ments in watches, &c., I included a sector adapted for sizing small wheels and pinions, 
by which the calibre (distance between the centres) of the wheels may be found. 
A specimen of the Genevese watch-sector, and one of each of the other sectors 
above referred to, were produced; also a jointed and a straight sector for sizing 
mill-gear, both of which had the allowance of two divisions for the length of the 
teeth beyond the pitch-line. 
The Excentric Sheet-Metal and Wire- Gauge. 
By Ricuarp Roserrts of Manchester. 
A plate of brass, about four inches and five-eighths diameter, and a quarter of an 
inch in thickness, is recessed on the upper side to the depth of an eighth of an inch 
and diameter of four inches, leaving a margin of five-sixteenths of an inch broad. 
In the centre of the recess is a hole, into which is fitted a steel pivot, whose upper 
end is riveted into a steel disc three inches and eight-tenths diameter and one-six- 
teenth of an inch thick; the pivot is excentric to the disc one-tenth of an inch, and 
consequently one point in the periphery of the disc touches the inner edge of the 
brass margin, with which the top of the disc is level. To the under side of the brass 
plate a small slide is fitted, to the outer end of which is attached (by screws) a piece 
of steel that passes up through a notch in the brass margin about half an inch, and 
forms the inner or sliding jaw of the gauge; the outer jaw is formed of a similar 
piece of steel, also passed through the notch in the brass margin, and is attached to 
the brass plate by screws. 
The inner edge of the sliding jaw is rounded to a radius of one-sixteenth of an 
inch, and is kept in contact with the periphery of the excentric disc by a spring 
(under the disc), which acts against a stud in the slide, projecting through the brass 
plate. The margin of the brass plate is divided through one-fourth its circumference, 
commencing at the centre of the sliding jaw, into seventy-five equal parts, which 
are numbered decimally. The extremity of the disc is then set at zero on the scale, 
and the jaws accurately adjusted to touch each other, after which the extremity of 
the disc is turned to the tenth division, and a line is made on the disc to correspond 
with zero on the scale, at which point the jaws will be open a little. The disc is 
turned to the required gauge-number by means of a milled button or two studs, and 
is fixed there by a milled nut, on the end of the pivot below. 
It may be convenient to have the numbers extended from seventy-five on a fourth 
of the circumference to one hundred on a third ; but the law of increase in the sizes 
above sixty-five would be reversed. It will be obvious that gauges having different 
numbers and dimensions may be more suitable for certain descriptions of work, and . 
likewise that the excentric principle may be applied to gauges in various ways. 
The excentric metal gauge possesses the following properties :—First. A corre- 
sponding gauge may be made, without expensive tools, from a written description 
of the means employed to make the original. Secondly. It admits of accurate con- — 
struction and easy readjustment. Thirdly. Each succeeding number being larger 
than the preceding in a progressively increasing ratio, adapts the gauge equally well 
for high and low numbers. 
N.B. The extentric gauge is not recommended for the workshop, butasastandard _ 
to make and test shop-gauges by. 

Mr. Richard Roberts of Manchester described, by reference to drawings, his patent 
apparatus, by which the influx and efflux of the tide are rendered available as agents 
for effecting (by hoisting weights for that purpose) the motions of clockwork ; thus, 
on a shaft, in connection with the clockwork, or other apparatus requiring motive 
power, a chain-wheel (No. 1), provided with studs or projections to prevent the 
chain slipping, is made fast; on a second shaft, which may be in line with the former 
one, is a similar chain-wheel (No. 2), also made fast ; over each of the chain-wheels — 
one side of an endless chain is passed, so as to form a loop on each side the shafts; — 
from a pulley in one of the loops formed by the chain the going-weight is sus- 
pended, and from a pulley in the other loop is suspended the counter-weight (the 
going-weight being heavy enough to actuate the clockwork and raise the counter- — 
weight), by which arrangement, if the second shaft be kept stationary, the clock- ~ 

