xlviii 



Finally, in 1864, he moved the Government of India to undertake the 

 series of pendulum observations at various stations of the Great 

 Trigonometrical Survey, from the sea level at Cape Comorin to the 

 lofty tablelands of the Himalayas, which have thrown so much light 

 on the constitution of the earth's crust, and on local variations of 

 gravity. 



The year 1826 was marked by his happy union with Miss Elizabeth 

 Juliana Leeves, daughter of William Leeves, of Tortington, thence- 

 forth his inseparable companion, his invaluable and devoted assistant, 

 and latterly his vigilant guardian, until their union was dissolved by 

 her death, in 1879, after fifty- three years of married life. Her 

 mastery of the German language was something exceptional. She 

 made herself competent to share in every investigation her husband 

 undertook, and habituaJly examined and checked his work ; suffice it 

 to say that thenceforward his powers were doubled. 



Captain Sabine's next service, after the publication of his pendulum 

 experiments, was as a Joint Commissioner, in 1825, with Sir John 

 Herschel, to take part with a Commission, nominated by the French 

 Government, to determine the precise difference of longitude between 

 the observatories of Paris and Greenwich, by means of rocket signals. 

 Herschel and M. Largeteau were the observers on the French side of 

 the Channel at Lignieres, Captain Sabine and Colonel Bonne on the 

 British side, at Fairlight Downs, near Hastings. The difference of 

 longitude thus found was 9 m. 21*6 s., which was believed to be not 

 more than one-tenth of a second in error, and extremely unlikely to 

 prove erroneous to twice that amount. The accepted difference at 

 the present day of electrical signalling is 9 m. 21"0s., a slightly larger 

 error, but the determination was very close. In 1827, he compared 

 the length of the seconds pendulum and the magnetic force of the 

 earth at the same two stations. 



Having obtained from the Duke of Wellington, then Master- 

 General of the Ordnance, a general leave of absence from military 

 duties, as long as he could usefully be employed in scientific pursuits; 

 he became in 1827 one of the secretaries of this Society, to which he 

 had been elected a Fellow in 1818. This office he tilled down to 

 1829. 



The condition of Ireland in 1830 was, as it has been usually since, 

 one to occasion the gravest anxiety. There was a failure of the 

 potato, from the effects of a cold wet summer; local famines; an 

 epidemic of influenza ; constant collisions between the peasantry and 

 the police. Under such circumstances Captain Sabine was ordered 

 to join his company : he served with it, or occasionally on the Staff 

 of his friend General Sir James Douglas, K.C.B., for the ensuing 

 seven years, and acquired the character of being a very "smart 

 officer:" but the time was by no means lost to science. He published 



