USEFUL P R O J ECTS. 



859 



than five feet ; the lo-.vcr series of 

 beams should be planked outside, 

 the same as the rest of the vfssel, 

 "which thus forming the bottom of a 

 third vessel in the midst of the 

 other two, should slope gradually 

 upwards at either end, tiiat it might 

 both make less resistance to the 

 waves, and tend to rise over them 

 when it encountered them. This 

 middle vessel, instead of being en- 

 tirely sustained by the other two, 

 might be constructed so as to draw 

 a foot or two of water, which would 

 both ease the strain on the others 

 greatly, keep up the licad of the 

 vessel against the depressing impulse 

 of the sails, prevent the sudden and 

 violint percussions which a flat 

 surface, suspended at a small dis- 

 tance above the waves, must suffer 

 from them in rough weather, and 

 ati'ord stowage for cables and a num- 

 ber of articles, without the bad 

 effect of loading on a part entirely 

 unsupported by the water, which 

 it otherwise must experience. 



The middle vessel, besides the su- 

 perior conveniences which it ^vould 

 ati'ord for stowage and lodging for 

 the crew, would also give g'Cat se- 

 curity in case of a dangerous leak 

 taking place in either of the side 

 vessels ; for by it the whole could 

 be so sustained, occasionally, tliat 

 it might be brought safe into port, 

 though one of the side vessels was 

 intirely water-loggcd. 



Double vciSfIs, of a large size, 

 ihould not be made to go with either 

 end foremost ; for, besiiies the im- 

 possibility of staying the masts pro- 

 perly for this purpose in lliem, tlicy 

 could not thus be shaped to the 

 greatest advantage for sailing swift; 

 for the head requiring a certain 

 fullness to bear up against the im- 

 pulse of the sails, and the stern a 



certain run, or length of slope, the 

 hciid also requiring the sloping or 

 rounding off to besidewise, and the 

 stern requiring the run, or sloping, 

 to be mostly from the bottom up- 

 wards, the shape which would be tit 

 f<jr one would not be fit for the 

 other, and an intermediate shape 

 would not be perfect either way. 



Small double vessels may have 

 the platform greatly strengthened' 

 by two or more pair of shears erec- 

 ted across it, each well secured to 

 the deck by a perpendicular shroud 

 descending to it from tlie upper 

 angle, or by a mast rising in that 

 part, well bolted (o the platform 

 below, and firmly fastened to the 

 shears above : it is imagined the 

 shears in the first of Sir Sydney's 

 boats might have been for this pur- 

 pose. 



In concluding, it is proper to no- 

 tice another species of vessels, pro- 

 jected by ]Mr. Gordon before men- 

 tioned, which he averred would have 

 all the good properties of the 

 double vessels, be much stronger, 

 have much more stowage, and re- 

 quire less timber in their construc- 

 tion ; and which certainly are 

 worthy of a fair trial. These vessels 

 were to be very flat, draw very 

 little water, and have their capa- 

 city in length and breadth chiefly J 

 and to prevent making leeway, 

 they were to have beneath their 

 flat bottoms a number of deep nar- 

 row keels, three or four feet from 

 each other, and were to be furnised 

 with two or more ruddcrs^each, if 

 one was not found sufiicient for their 

 management. 



On the cleaning of Engravings with 



ox^'genatcd muriatir. jdd. Bi/.AL 



J> L. Hoard. 



