170 DYNANOMETE R. 
Thisinftrument, though very ingenious, has not proved 
adequate to the purpofe intended. Therefore, to remedy 
its defeats, an improved dynanometer has been recently 
invented by M. Regnier, of the Polytechnique (drool. 
Belides the ufe which an enlightened naturalift may make 
of this machine, it may be poffible to apply it to many 
other important purpofes. For example, it may be em¬ 
ployed with advantage to determine the ftrength of 
draught cattle ; and, above all, to try that of lrorfes, 
and compare it with the flrength of other animals. It 
may ferve to make known how far the alTifhnnce of well- 
conftrulled wheels may favour the movement of a car¬ 
riage, and what is its vis inertia in proportion to the load. 
We might appreciate by it, alfo, what refinance the Hope 
of a mountain oppofes to a carriage, and be able to judge 
whether a carriage is fufficiently loaded in proportion to 
the number of horfes that are to draw it. In the arts, it 
may be applied to machines of which we wifh to afeertain 
the refiftance, and when we are defirous to calculate the 
moving force that ought to be adapted to them. It may 
ferve, alfo, as a Roman balance to weigh burdens. In 
lhort, nothing would be more eafy than to convert this 
machine into an anemometer, to difeover the abfolute 
force of the wind, by fitting to it a frame of a determined 
lize, filled up with wax cloth; and it would not be im- 
poflible to afeertain by this machine the recoil of fire 
arms, and confequently the flrength of gunpowder. 
This dynanometer, reprefented at C, in the annexed 
engraving, confifts of a fpring twelve inches in length, 
bent into the form of an ellipfis; from the middle of 
"which arifes a femicircular plate of brafs, having en¬ 
graved upon it the difi'erent degrees that exprefs the force 
of the power ailing on the fpring. The whole of this 
machine, which weighs only two pounds and a half, op¬ 
pofes, however, more refiftance than may be neceffary to 
determine the altion of the ftrongeft and moft robuft 
Jiorfe. The fimplicity of its mechanifm will be better 
illuftrated by the following defeription : A, an elliptical 
fpring, feen in perfpeltive, covered with leather, that it 
may not hurt the fingers when ftrongly prefl'ed on with 
the hands. This fpring is compofed of the beft Reel, 
well welded and tempered, and afterwards fubjelled to a 
ftronger proof than is indicated by its graduation, in order 
that it may not lofe any of its elafticity by life. B, a 
piece of fteel ftrongly fattened to the fpring by means of 
a claw and ferews, in order to fupport the femicircular 
plate of brafs C, mounted on the fpring, feen geometri¬ 
cally. On this plate are engraved two arcs, one divided 
into myriagrammes, and the other into kylogrammes.. 
.Each of thefe arcs is (till farther divided by points, 
which exprefs the weight in pounds de marc ; and all thefe 
degrees having been exaltly valued by accurate weights, 
it thence refults that all dynanometers of this kind may 
be compared with each other. D, a fmall fteel fupport, 
adj lifted like the former to the other branch of the fpring, 
and having a cleft towards its upper extremity to receive 
a fmall copper lever E, which is kept in its place by a 
fmall fteel pin a. The whole of this mechanifm is feen 
at H, of its full fize. F, a fteel index, very light and 
elaftic, fixed upon its axis by a ferew in the centre of the 
brafs femicircle. This index has a fmall bit of leather 
or cloth glued upon the fmall circular part G, in order 
r.o render the friction on the plate eafy, uniform, and al- 
moft infeufible. It is to be obferved, that this index is 
terminated by a double point- adapted to the divifions on 
both the femicircular arcs. The firft, divided into my- 
riograinmes and points, exprefimg ten pounds de marc , 
ferves for all experiments which oblige the fpring to be 
elongated in the direction of its greater axis, as is the cafe 
in trying the ttrength of the body : in a word, for all 
trials where it is weceifary to draw the fpring by the two 
ends. Thefecond, divided into kylogrammes and points, 
exprefimg pounds de marc, is deftined for experiments 
which compreJ% the two lidesof the fpring, as in trying the 
force of the hands. I, a fmall plate of brafs which co¬ 
vers the mechanifm, to prevent it from being injured. 
This fmall.plate has on it alfo a divided arc, the degrees 
of which correfpond with tho(e of the firft arc of the 
machine ; and by the play of a fmall index b, which is 
under the plate, the movements of the fpring may be af- 
certained. K, an aperture in the covering plate, through 
which may be introduced a fmall turnferew, for the pur- 
pofe of tightening or eafing the index as may be necef¬ 
fary. L, a pallet of brafs, with a ferew, having a cap 
like that on the needle of the mariner’s compafs, in 
which the lower pivot of the lever, that putties round 
the index or handle, is made to play. This pallet, ail¬ 
ing as a fpring, yields to any bidden fltock, and prevents 
the derangement of the mechanifm. M, a focket ri¬ 
veted on the plate I, in which the upper pivot of the 
lever turns. N, N, N, fmall cylindric pillars that fup. 
port the covering plate, which is fixed to them by three 
ferews. O, an iron rack, on the lower part of which the 
feet mull be placed when it is intended to try the flrength 
of a perfon’s body. P, a double handle of wood, with 
an iron hook, to be held at the fame time in the two 
hands. Q, a double hook made of iron, one end of which 
is to be hooked to the end of the fpring, and the other 
to a rope fattened to a poft, as at c, when experiments are 
to be made on the ftrength of horfes, or others, that re¬ 
quire the dynanometer to be lupported by hooks. R, the 
manner of holding the dynanometer by perfons who wifh 
to afeertain the ftrength of the hands. S, pofition of a 
man when trying the ftrength of his body. T, difpofition 
of the dynanometer to try the ftrength of a horfe, or any 
other draught animal. 
The effelts of this machine may be thus explained; 
If a perfon preftes on the fpring with the hands, or draws 
it out lengthwife, by pulling the two extremities in a 
contrary dire&ion, the two lides of the fpring approach 
each other ; and in proportion as they are brought nearer, 
the fmall lever of the mechanifm pufhes before it the 
index, which, by the tightnefs with which it is fere wed 
in its place, will remain at the point to which it has been 
brought by the pin d, in confeqttence of the force ailing 
on the fpring. The mufcular force of the arms, or rather 
the ftrength of the hands, may be tried by laying hold of 
the two fides of the fpring neareft to the centre, as may 
be feen in figure R; fo that the arms may be a little 
ftretched, and inclined downwards, almoft at an angle of 
forty-five degrees. This pofition, which appears the 
moft natural, is alfo the moft convenient for a man to all 
with his full force. It is to berecolIdled, that the lower 
arc ofdivifion, divided into kylogrammes, is that which 
ferves to exprefs the force of the hands, and of all the 
allions which pre/s the two fides of the fpring. The 
ftrength of the hands may alfo be tried one after the 
other; and if an account be kept of the degree of prefi. 
fare of the right hand, and then' of the left, and thefe 
two fums be added together, it will be found that the 
fum-total is, in general, equal to the ftrength of both the 
hands when acting together. 
To try the ftrength of the body, the perfon mutt place 
his feet on the bottom part of the rack O ; one of tlie 
ends of the fpring is then to be placed in one of the 
hooks of the rack; and the hook P is to be put into the 
other end. In this pofition the body is perpendicular $ 
the lhoulders only being inclined a little forwards, to be 
able, in throwing back the body, to pull the fpring with 
all the force which a perfon is capable of exerting. In 
this lituation, reprefented by S, a man may ra’ife a great 
weight without being expefed to thofe accidents which 
might be occafioned by an effort made in a more coa- 
ftrained pofition. 
Nothing can be more convenient than this dynanometer 
to afeertain and compare the ftrength of horfes, and that 
of all draught animals. The apparatus at T, (hews in a 
fufficient manner, the difpolitions neceffary for experi¬ 
ments of that kind. The trials made by the inventer 
ferve to give a very juft; idea of the abfolute force of 
.horfes 
