68 Kolicei respecting ycxv Books. 



This new railway consists of a single rail supported by 

 equidistant pillars ; it is raised above the common surface of 

 the ground to the height of about 3 feet; and the load is sus- 

 jiended from the axles of two Avheels which run one before 

 another on the upper edge of the rail. The construction o( 

 the frame is such, that the centres of suspension of the load 

 are below the virtual centre of support; therefore the equilibrium 

 is always stable, the virtual centre of support being equivalent 

 to the metacentre of a ship*. But since the load on each side 

 of the rail ma}' happen to be unequal, the change of position, 

 which would be a necessary consequence of this unequal distri- 

 bution, is counteracted by the breadth of the surface of the rail ; 

 and the stability may be greatly incieased, if necessary, by add- 

 ing braces to t!ie bars which suspend the load to the axles. 



By adopting this railway, a perfectly even and adjustable 

 plane with a very small degree of resistance may be obtained : 

 elevated so as to be free from dust, or other extraneous mat- 

 ters, " no further preparation is requisite for the moving power 

 than an ordinary towing-path. The horse draws by a towing- 

 rope connected to the carriages, and proceeds on one side of 

 the rail ; and as his height will var}' with the natural undula- 

 tions ot the surface of the ground, he will sometimes be below 

 the surface of the rail, and is consequently jirovided with a 

 length of rope which allows a considerable variation of height 

 without much altering the angle of traction." 



The various contrivances that may be employed to ren- 

 der loading and imloading, passing, crossing roads, brooks, 

 rivers, ravines, &c. easy and simple, ai'e i'ully described, and 

 illustrated by two beautiful engravings. But the author has 

 not confined his work to a description of his ingenious rail- 

 way alone; he gives some interesting particulars respecting 

 other kinds of railways, with a table of experiments showing 

 the effect produced by a given power on different kinds of rails. 

 Also some very curious remarks on tlie friction of axles, and 

 a description of an improved dynamometer on a principle 

 analogous to that which Coulomb employed to check the irre- 

 gular oscillations of delicately suspended needles in his ex- 

 periments on magnetism. 



It appears, from the experiments described in the work, 

 that, allowing the force of a horse to be 150 lbs, one horse will 

 be capable of drawuig about 20 tons upon a level railway on 

 Mr. Palmer's princi])le ; on a good hard and level turnpike 



* Our readers will find thi^ principle of stability illustrated in a recent 

 ■work on the Elements of Natural Philosophy, bv Professor Leslie, where it 

 is applied to explain the rnrious pha^nomcna of rockinp or iaggan stones, 

 road a horse of the same power could not draw more than 



about 



