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the history of various arts, especially those of steam navigation and 

 the manufacture of textile fabrics. The results are partly embodied in 

 the " Sketch of the Origin and Progress of Steam Navigation" (1848), 

 and " Brief Biographies of Inventors of Machines for the Manufacture 

 of Textile Fabrics " (1863) . Yery little of the material collected during 

 the later years of his life has, however, been given to the world. The 

 peculiar bent of his mind showed itself also in the formation of the 

 Patent Office Museum, which was first opened to the public in Juue, 

 1857. The collection is small, but it embraces a number of machines 

 and models of the highest historical interest, many of which would 

 have been destroyed or suffered to fall into decay but for Mr. 

 Woodcroft. Forming part of the Museum, was a collection of por- 

 traits of inventors and authors of discoveries in connexion with the 

 useful arts. A considerable portion of his private fortune was 

 expended in the purchase of portraits and objects for the Museum, 

 but partly in consequence of the want of a proper building, the 

 Museum has not attained that importance which was hoped for by its 

 founder. The late Prince Consort took a warm interest in the 

 scheme. 



Mr. Woodcroft's inventions embraced subjects connected with 

 weaving, marine propulsion, and dyeing. His " tappet " for looms, 

 which was patented in 1838, is now in universal use in looms for 

 weaving a certain class of goods. From an early period in his life he 

 had paid great attention to the subject of marine propulsion, and in 

 1832 he obtained a patent for his well-known increasing pitch screw 

 propeller, which Lord Brougham, in the course of a judgment in the 

 Committee of Privy Council, spoke of as "a very refined and in- 

 genious contrivance." In all the screws previously suggested the 

 blade had a uniform pitch or incline, but Woodcroft's screw is formed 

 by a blade so coiled round a shaft or cylinder that the angle of 

 inclination of the worm with the axis continually decreases, and the 

 pitch or distance between the coils continually increases throughout 

 the whole length of the shaft upon which the spiral is formed. In 

 consequence of this elongation of pitch each successive part of the 

 spiral begins to act before it is overtaken by the current given to the 

 water by the action of the preceding part, and consequently every 

 part meets with resistance from the water. In this way a proportion 

 of propelling power is gained and loss from slip is avoided. He also 

 patented a "varying pitch" screw propeller, the object of which 

 was to enable the angle of the blades to be altered at pleasure, accord- 

 ing to the varying circumstances of wind, currents, or tonnage. In 

 the course of his business as a dyer, he had been struck with the 

 difficulty of printing calico with indigo, in consequence of the rapid 

 oxidation which takes place, and he made a series of experiments on 

 the practicability of carrying on the operations in an atmosphere of 



VOL. XXIX. ^ 



