In the accompanying illustration we show a new design of hand car, being introduced by the Courtright Manufacturing Co., of Detroit. It will be seen that the apparatus for propelling the car is very different from the mechanism generally used. An upright framework secured to the platform carries a large sprocket wheel, which is connected to a smaller one upon one of the axles by means of a chain. The larger sprocket wheel is rotated by means of a triangular shaped lever attached at the lower corner to the crank of the sprocket wheel and having a handle at each of its upper corners. It is hinged upon a fulcrum which slides upon the two vertical rods shown in the illustration. It will be seen that this gives a peculiar movement to the handles by which the operators propel the car, but it has been found that the motion is an excellent one, and it is claimed that a higher speed can be obtained with the mechanism here shown than with any other now in use. There is practically no dead center, as in the case where the ordinary crank and lever is used. A number of leading roads have given the car a trial, and being well satisfied it, have given orders for more. The company claim that a car with 20 in. wheels can easily be made to attain a speed of 15 miles an hour by two men.--_Railway Review_. * * * * * THE CONIC SECTIONS. By Prof. C.W. MACCORD, Sc.D. In Fig. 1 let D be a given point, and O the center of a given circle, whose diameter is FG. Bisect DF at A. Also about D describe an arc with any radius DP greater than DA, and about O another arc with a radius OP = DP + FO, intersecting the first arc at P, then draw PD, and also PO, cutting the circumference of the given circle in L. Since PD = PL, and DA = AF, it is evident that by repeating this process we shall construct a curve PAR, which satisfies the condition that _every point in it is equally distant from a given point and from the circumference of a given circle_. Since PO-PD = LO, and AO-AD = FO, this curve is one branch of the hyperbola of which D and O are the foci. [Illustration: FIG. 1] Bisect DG at B, then about D describe an arc with any radius DQ greater than DB, and about O another are with radius OQ = DQ-FO; draw from Q the intersections of these arcs, the line QD, and also QO, producing the latter to cut the circumference in E. By this process we may construct the curve QBZ, each point of which is also equally distant from the given point D, and from the concave instead of the convex arc of the given circumference. The difference between QD and QO being constant and equal to FO, and AB being also equal to FO, this curve is the other branch of the same hyperbola, whose major axis is equal to the radius of the given circle.