DOLLOND. 49 



electro-chemical action, succeeded in preventing it, by attaching 

 plates of iron or zinc to the copper. This, however, on being tried 

 practically, introduced the unlocked for evil, of excessive fouling of 

 the bottoms of ships so protected, which became liable to marine 

 deposits in an equal manner with wooden bottoms. Davy's plan 

 was thus rendered utterly useless, much to his mortification. 



During the later portion of his life, Sir Humphry was in very 

 infirm health, and in 1828 he determined to go abroad. Proceeding 

 into Italy, he fixed his residence at Rome, whence he sent his last 

 communication to the Royal Society, viz., ' Remarks on the Elec- 

 tricity of the Torpedo.' The chief peculiarity of this paper was the 

 discovery that the electricity of this curious creature had no effect 

 on the most delicate galvanometer. While staying at Rome, Sir 

 Humphry was seized with a paralytic attack, which greatly alarmed 

 his friends. Shortly afterwards he left Rome for Geneva, on reach- 

 ing which city an attack of apoplexy seized him during the night, 

 which terminated fatally. The funeral took place on the 1st of 

 June, 1829, with all the honour and respect the inhabitants of Ge- 

 neva could testify. His remains were deposited in the burying- 

 ground of the city, without the walls, the spot being marked by a 

 simple monument, with a Latin inscription, erected by Lady Davy. 

 Life of Sir H. Davy, by his brother, John Davy, M.D., F.R.S. 

 London, 1839. Memoir by Dr. Thomas Trail, Encyclopedia Britan- 

 nica. Weld's History of the Eoyal Society, with Memoirs of the 

 Presidents. London, 1848. Brougham's Lives of Philosophers. 

 London and Glasgow, 1855. 



PETER DOLLOND. 



Born February 2, 1731. Died July 2, 1820. 



Peter Dollond, the subject of the present memoir, was the eldest 

 son of John Dollond, the celebrated inventor of the Achromatic 

 Refracting Telescope, who, during the greater portion of his life, 

 was engaged in the business of a silk-manufacturer, in Stuart Street, 

 Spitalfields. Here Peter Dollond was born and spent the early 

 portion of his life. On reaching manhood he engaged in the same 

 occupation as his father, and for several years they carried on their 

 manufactures together in Spitalfields. Peter Dollond had, however, 

 acquired some knowledge of the theory of Optics, and he deter- 

 mined, if possible, to turn the knowledge he had gained to the 

 improvement of himself and his family. He accordingly com- 

 menced business as an optician, under the direction of his father, in 



D 



