158

the vibrating

TRACT 35.

8. Construction and Description of the VibratingEprouvette.

Plate 3 shows the machine, and its several parts, in variouspositions, as fitted up with a brass gun, the length of whichwas indies, the diameter of its bore being n inc. andconsequently capable of receiving an iron ball of near 11-Aounces in weight: the dimensions of all the other parts maybe measured bv' means of the annexed scale of feet andinches. In the plate, fig. 1 exhibits a side view or elevationof the machine at rest, with its stand or support. Fig. 2 is afront view of the same; fig. 3 a perspective view, with thegun having vibrated backwards ; fig. 4 is an orthographicprojection of the frame or stand, as seen by an eye placedvertically over it; and fig. 5 shows some of the parts sepa-rately.

Fig. 1 then exhibits the manner of suspending the gun byits axis ; of connecting it to the two steel branches a, b, ofthe stem ; as also of the quadrant cd, to the same, with itsindex fcg-, where eg is the part of it which rests upon a stopor small bar ( kl in fig. 4) fixed across the upper part of thestand.

In fig. 2 are seen some of the same parts, with the steelaxis hi, upon which the gun and arch vibrate.

In fig. 3 are seen the same things, each denoted by thesame letters as in all the other figures.

In fig. 5 are exhibited the steel axis hi, the axis ,feg, of thearch, with the part or arm eg, which rests on the stop partkl, to prevent the axis from recoiling back with the gun inthe first vibration, and having two open notches near the end/, for viewing the different lines of divisions on the limb ofthe arch : ni, n, show the socket and spring, for producingthe gentle pressure of the socket e of the index, against thesocket 0 of the axis, by means of the key p behind it.

9. Though the machine is here represented as fitted upwith a small gun, it is to be understood that it may be equallywell made with a small mortar, or a very short gun ; which