862 TiiA.\SA('Tfoxs OF Tilt: Amebic Ay Institute. 



gimlet-pointed, uud also milled out on three sides in the manner of a 

 steel " tap " for cutting threads in metals — as to he readily forced to 

 their place in the hardest timber, and through the hardest knots 

 without the labor and time of boring holes. ^ 



The process of using these screws is readily accomplished by giving 

 to the screws a large, square head, and having a " key," fashioned 

 precisely like a common boring auger ; but, instead of the spur and 

 twist, there is, upon the lower end of the shank, a strong steel bulb, 

 having a square socket, which easily fits the head of the screw. 

 Now, the screw being set to its place, and partially started by giving 

 it one or two blows vnih a heavy hammer, the auger key completes 

 the operation ; for, by means of its level's, the screw is turned dovm 

 to its holding position in the same time and as easily as to bore similar 

 holes for spikes or common bolts. 



By the introduction of these continuous lines of chairs or brackets, 

 we have a uniform combination rail, and are enabled to dispense with 

 all kinds of small plates, chairs and fish-bars at the points of the rails ; 

 amd, by breaking the joints of the brackets with themselves, and also 

 with those of the rails, distributing all the points of all the parts regu- 

 larly and equally, we obtain the utmost uniformity of strength and 

 security, and guard the rail proper thoroughly and completely against 

 displacement in case of breakage ; for, if a rail become broken in any 

 number of places, unless the line of breakage chance to take a hori- 

 zontal direction above the bracket, and the piece be thrown out, a 

 train of cars may pass over it as safely as if it were entirely whole, a 

 break in a perpendicular direction always being quite harmless ; 

 becoming simply an additional joint. 



By this arrangement, we also gain another very important advan- 

 tage ; the ends of the rails and brackets do not require to be secured 

 by passing spikes or bolts through holes or notches made therein, 

 being held to their place entirely by clamping with the dogs ; thus 

 allowing sufficient freedom for expansion and contraction by extreme 

 changes of temperature, dispensing with holes and notches in both 

 rails and brackets, giving complete uniformity of strength and sta- 

 bility. 



In the second model, Ave show an improved form of rail, one having 

 tlie general form of a cone, the base of which is divided by the intro- 

 duction of a central arch ; whereby the bearing is shared by two equal 

 branches, and all the material and strength of the rail secured to the 

 crown and outer sides. 



