izj,o Sir George Shuckburgh Evelyn's Endeavours 
exist; and, from its shape and quality, it maybe considered as in- 
flexible in any ordinary experiments. At p is a small adjusting 
screw, which raises or depresses a weight within, and with it, 
in consequence, the centre of gravity of the whole beam ; by 
this means, the motion on its centre may he brought to almost 
any required degree of sensibility. Should the centre of gra- 
vity be raised above the centre of motion, the beam would turn 
over ; if it be in that centre, the beam would stand any where 
indifferently, without any vibration ; if it be placed much below 
it, the vibration would be too quick, and its sensibility not suffi- 
cient: it is therefore brought, by the screw p, a very small quan- 
tity below the centre of motion, so as to describe one vibration 
in 40 or 50 seconds; the sensibility is then fully sufficient. 
At each end of the beam are circular boxes, n and 0, through 
which pass the steel centres, from whence are suspended the 
scale-pans q and r : these centres resemble, in some degree, 
those at m, but have their chamfered or angular edges upwards, 
and thereon hang the hooks ( 3 , to which are affixed the links u, 
and to them the three silken lines of the scale. Each of these 
centres has a motion in its respective box, by means of two 
small adjusting screws ; that in 0 laterally, and that in n ver- 
tically ; the former to make the two arms of the beam of an 
equal length, the latter to bring the three points of suspension 
of the beam and scales into a right line. At the extremity of 
the boxes are fixed two needle points or indexes, which play 
against the ivory scale of divisions at s and t. These divisions,, 
although they do not, indeed they cannot, shew any definite 
weight, are nevertheless very useful in making the adjustments, 
and even in weighing to the small fractions of a grain, u v are 
two steady plates, that are raised or depressed by the wooden nut. 
