That disease which annually afflicts our country, and which may truly be called the "show fever," when any one who has an invention of any kind takes it to the State fair, and exhibits it to an appreciative multitude, is quickly coming—the season of exhibitions and fairs will soon be upon us, and we have to call attention to a most useful invention, which will be of great value to the judges who award the prizes. The invention which our engravings illustrate—Fig. 1 being a front elevation, and Fig. 2 a back view—is a dynamometer of simple and improved construction, the invention of G. and ,T. W. Gibbs, of Canton, Ohio, and patented by them August 26, 1856. It is suitable, and will, we have no doubt, be extensively used for trying the draft of wagons, plows, reapers, mowers, c, and the strength of cattle, horses, c. ; in fact, it measures force in nearly all of its thousand applications. It consists, as will be seen on reference to the , engravings, of an elliptical spring, the advan-|tages of which over the spiral (usually em- ployed) are too well-known to need recapitulation. The spring, A, is flattened out at its ends, B, and to the upper branch is attached an index, C, on which two pointers, D and E, moving on an axis, F, indicate the power exerted. One end, B, being attached to the ob-j ect whose draft is to be tested, the horse or other motive power is attached to the other end, and as the strain comes on the spring it brings the two curves, A, nearer together ; in so doing the bar, H, being attached at G to one curve, is pushed up, and being pivoted to a lever, I, on a small gear wheel, J, it turns that partly round, and so moves K, which is rigidly connected to the axis, F. This, of course, causes the pointer, D, to move round the dial, and the whole being proportioned and graduated correctly, the indicator, E, being only loosely placed on the axis, F, vibrates as the implement to be tested is drawn along, and indicates the average draft very accu rately. It is light, simple, and perfect in its opera- tion, and is manufactured, or the patent is for sale by Gibbs &Danner, of Canton, Ohio, who will give any further particulars. The committee of the Ohio State Board of Agriculture highly commend it; and the Secretary says that " it is the only instrument of the kind he is acquainted with that is at all times reliable."