IX. NA.VAL AKCIIITECTUTii:,. ETC. 499 



Government, and set up in Portsmouth Dockyard by Messrs. 

 Maudslay and Sons in 1804, where it has remained in use to the 

 present time. Royal Naval Museum, Greenwich. 



2169a. Model of Wrought-iron Ship's Block, by the 



exhibitor. The late Baron Seguier, Membre de Vlnstitut. 



20 7O. Flan for Feathering a Screw Fropeller, proposed 

 by Messrs. Maudslay, Sons, and Field, 1848. 



Royal Naval Museum, Greenwich. 



2171. Hirsch's Screw Propeller. 



Royal Naval Museum, Greenwich. 



2172. Four-bladed or Two-bladed Screw Propeller. 



Royal Naval Museum, Greenwich. 



2173. Working Model of a pair of Inverted Cylinders 



Marine Engine for driving a screw propeller. Cylinders 

 2J inches bore, stroke 4 inches, link motion and reversing gear 

 complete, shut-off valve, &c. Full sized partly shaded drawings of 

 same. Made by exhibitor during his apprenticeship. 



Robert Lathbury. 



2174. Model in mahogany of a Three-bladed Griffiths 9 

 Fatent Screw Fropeller. Made by exhibitor during his 

 apprenticeship. Robert Lathbury. 



2178dn. Model of Small Steamer << Mab," the fastest on 

 the Neva. Built in 1874, of brass, by George Baird, St. Peters- 

 burg. 



Length - - - - 48 ft. 



Breadth - 6 ft. 6 in. 



Depth at side - 3 ., 6 



Draught - - - - 1 7 



over screw - - . - 2 9 



Speed - 19 miles. 



Diameter of high pressure cylinder - 7 ins. 



low - 11 



Stroke - - - - 8 



1 Working pressure "-*- * - 120 Ibs. 



Revolutions per minute - 600 



Nominal H.P. - - - 8 



George Baird, St. Petersburg. 



2178b. Model of a Yarmouth Herring Fishing Lugger 



getting her nets in. Exact model and position of men when at 

 their work. John Bracey. 



2178c. Model of a Yarmouth Trawling Smack. With- 

 out the trawl net. . John Bracey. 



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