On Artificial and Natural Arrangernents of Plants. 97 



in voyages from Trieste to Venice, and it gave the greatest 

 satisfaction to the parties making the trial, shortening the voy- 

 age by two hours, and causing a great saving of coal. The 

 plan is simple, and a wheel constructed upon it would have 

 very little friction. The paddles may be renewed in a few 

 minutes, as they are screwed and dowelled on, so that a broken 

 paddle may be removed, or one of a different size fixed on, 

 with the greatest ease; and the inclination, or dip and rise of 

 the paddles can be changed in five minutes, by a set-scretv on 

 the fixed or eccentric crank. 



A working model of this paddle-wheel, on the scale of an 

 inch to a foot, was completed by me in January last (1829) ; 

 it was shown to various gentlemen engaged in steam-naviga- 

 tion and the manufacture of machinery ; and in the beginning 

 of August last, it was placed in the hands of Mr. — Morris, 

 parchment-manufacturer, of Long-Lane, Bermondsey, who 

 kindly endeavoured to introduce it to the notice of some parties 

 high in office. It remained with him for about three months, 

 and was deposited for exhibition in the National Repository 

 of Arts, King's Mews, on the 12th of November last. 



On die 14th instant, I removed it from the gallery, for the 

 purpose of showing it to Mr. Richard Taylor, to whom a 

 drawing and description of it had been previously submitted 

 for publication in the Philosophical Magazine and Annals of 

 Philosophy ; and it now remains in my possession, and may 

 be inspected by any person who may wish to examine it. 



Should any gentleman engaged in the construction or ap- 

 plication of machinery to steam-navigation be desirous of try- 

 ing paddle-wheels on this principle, I shall be happy to con- 

 struct a model, in which the principle will be simplified, and 

 the expense of construction of the wheel materially reduced. 



5, Old George-Street, Suffolk-Street, KiNG WiLLIAMS. 



South wark, Dec. 21, 1829. 



XIIL OnArtiJicial and NaturalArrangements of Plants : arid 

 particularly on the Systems of Linnaeus and Jussieu. By 

 William Roscoe, Esq. F.L.S. 



[Continued from page 23.] 



TNSTEAD of dwelling further on the endeavours of the 

 -*■ French botanists to invalidate the labours of Linnaeus by 

 resorting, as Ventenat lias done, to the well-known censures of 

 Haller and others, I shall in the sequel of this paper endeavour 

 to ascertain the relative merits o< the two systems which now 

 N.S. Vol. 7. No. 38. Feb. 1830. O principally 



