Nautical Economy, o3 



A great deal of Irrelevant demonstration has been inju- 

 riously applied to prove the excellency of the diagonal 

 riders. There are no sources of error and confusion so pro- 

 lific as inappropriate analogies. To liken thirty bending 

 riders, in the curved bottom of a ship, to the straight cross- 

 bar of a common field-gate, is an assimilation so unapparent, 

 that we are surprised how it could ever be adduced *. If 

 the side of a ship were perpendicular, and one cross-timber 

 reached from the hold in midships to the extremity forward, 

 and another aft, the comparison would be more admis- 

 sible. But, in that case, there would still be great dis- 

 similarities : the side of a ship is planked from the top to the 

 bottom, and this coating is so close, as to prevent the ad- 

 mission of water; while the bars of a gate are only intended 

 to prevent cattle getting through. A ship is six or seven 

 times in length of hold what it is in depth ; whereas a gate 

 is only about twice the length of its height. In the case of 

 a ship dropping at its extremities, the upper-works must 

 lengthen ; whereas, in a gate, this deformation takes place 

 by a revolution on the fastenings, by which the bars ap- 

 proach each other, and which the planks of a ship are 

 prevented from doing by their immediate contiguity. — 

 If this train of reasoning can be allowed, it will only apply 

 to the mode of placing the diagonal riders, adopted by 

 surveyors, previously to Sir Robert, as exemplified in the 

 top-sides of the Caledonia, — a ship which has received an 

 universally good character. But the question can only be 

 determined, as we have observed, by general results. 



Some persons have supposed, that, in the diagonal S3^stem, 

 the strains are transmitted endwise on the fibres, in which 

 direction wood is the strongest ; but it is evident, that if the 

 enormous angular momentum, producing the working of a 

 ship, depended for resistance on the bolts of a few cross- 

 riders, the strain would not be so well supported as by the 

 multiplicity of bolts in the thick stuff and ceiling covering 

 the concavity of the hold ; for this reason, we find Dupin, 

 in preference, recommending interior diagonal planking be- 

 tween wind and water. 



The resistance to arching must depend on the distance 

 at which the opposing force is applied from the neutral 



* A ship has been Hkened in this discussion to various other articles ; 

 even Indian rubber has been brought forward as an analogy, the appli- 

 cation of which we do not exactly perceive. By comparing it with the 

 moon, or any thing else, we may obtain any imaginable results we 

 may desire. 



JAN.— MARCH, 1827. D 



