Dent's new Compensation Balance for Chronometers. 89 
On an increase of temperature, the movable extremities of the 
segments approach the centre of motion, as represented by the 
dotted inner curve lines, and the reverse effect takes place on a 
decrease of temperature. Now, that the inertia may correspond 
with the tension, the compensation-weights, c, upon an increase 
of temperature, should approach the centre of the balance with 
an accelerated motion, and, upon a decrease of temperature, with 
a retarded one. On examination of this ordinary balance, it is 
evident that its action is directly opposed to the above requisition. 
And before further investigation of the subject, it is important to 
remember, that when metals of unequal expansion, such as brass 
and steel, are united, (as in the compensation-balance,) the ex- 
tremities of the lamine move in a spiral curve, on being influ- 
enced by change of temperature. I will now proceed to the 
explanation :—If we connect, by means of the dotted straight 
line d, the centre of gravity of the compensation-weight, with 
the junction of the lamine, at the arm of the compensation-bal- 
ance, and suppose a change of temperature from heat to cold to 
take place, the result will be, that the brass, which is on the out- 
side of the segments, contracts more by the increase of cold than 
the steel on the inside; hence the distance between the centre 
of gravity of the compensation-weights, and the junction of the 
laminee at the arm, is increased: in other words, the length of 
the chord of the arc, or dotted line, is, by the unfolding or 
straightening of the segment, augmented. Under such circum- 
stances the radius of motion and the increment of distance are 
increased, whilst from an increase of temperature the converse 
takes place, which is the very reverse of what should occur. 
For, by an increase of cold, the chord of the are d should be 
shortened, and lengthened by an increase of heat; a result which 
my present invention is designed to eflect by applying to the or- 
dinary compensation, which may be termed primary compensa- 
tion, the addition of a secondary continuous compensation, which 
will move the compensation-weights over a space more calcula- 
ted to accommodate the force of the inertia to the varying ten- 
sion of the balance-spring. 
In the drawings annexed, are representations of different modi- 
fications of my invention, given as exemplifications of the prin- 
ciples upon which my improvements are effected. 
Vol. xtv, No. 1.—April-June, 1843. 12 
