Page:Dictionary of National Biography volume 46.djvu/203

 

PORTLAND,. [See, third , 1738–1809; , fifth , 1800–1879.]

PORTLAND,. [See, first , 1577–1634; , second , 1505–1664; , first of the Bentinck line, 1649–1709.]

PORTLAND, titular. [See, 1648?–1698.]

PORTLESTER,. [See, d. 1496.]

PORTLOCK, JOSEPH ELLISON (1794–1864), major-general royal engineers and geologist, only son of Captain [q. v.], was born at Gosport, Hampshire, on 30 Sept. 1794. After passing through the Royal Military Academy at Woolwich, he received a commission as second lieutenant in the corps of royal engineers on 20 July 1813. He served for a short time at Portsmouth and Chatham, and was promoted first lieutenant on 13 Dec. 1813. In April 1814 he embarked to join the army in Canada. He took part in the siege of Fort Erie (August 1814), and for the greater part of it was the only engineer officer in the trenches. When the army retired he constructed the lines and tête de pont of Chippewa at which Lieutenant-general Sir Gordon Drummond made his successful stand and saved Upper Canada. For his services on this occasion Portlock was thanked in general orders. He was afterwards employed on numerous exploratory expeditions. Portlock Harbour in Lake Huron was named by Sir Gordon Drummond in memory of Portlock's services.

On Portlock's return to England in October 1822 the ordnance survey was about to be extended to Ireland, and in 1824 he was selected by Colonel [q. v.] for employment there. In the organisation of the Irish survey Portlock was the confidential assistant and companion of Colby, and he was retained at headquarters at the Tower of London while (1797–1840) [q. v.] and others were occupied with the construction of the new base apparatus and other instruments and details.

In 1825 Portlock accompanied Colby to Ireland, and remained attached to the trigonometrical branch of the work, of which he soon became the senior and ultimately the sole officer. In 1826 he was employed in the observations at Slievedonard, co. Down, 2,800 feet above the sea. This was a very exposed station. The camp was frequently blown down and the instruments with difficulty preserved. Conjointly with the observations and calculations of the horizontal triangulation, Portlock had to undertake a system of vertical observations and calculations for altitudes. He carried a line of levelling from the coast of Down to the coast of Donegal, and caused similar lines to be observed in other places crossing Ireland in every direction, and terminating at stations on the coast, where tidal observations were simultaneously made. These operations, in addition to their immediate and practical object, furnished the material for the admirable paper on tides, by the astronomer-royal, published in the ‘Transactions of the Royal Society of London’ in 1845.

On 22 June 1830 Portlock was promoted second captain. In 1832 it was arranged to compile a descriptive memoir of the survey. Portlock, having completed the great triangulation, undertook the portions of the memoir relating to geology and productive economy. In 1837 he formed a geological and statistical office, a museum for geological and zoological specimens, and a laboratory for the examination of soils. Unfortunately, for financial reasons, the preparation of the memoir was suspended in 1838, and was not resumed, although a commission, appointed in 1843 by Sir Robert Peel, recommended its resumption and continuance. Portlock published the volume, which bears his name, on the ‘Geology of Londonderry, Tyrone, and Fermanagh, with Portions of Adjacent Counties’ (with maps and plates, Dublin, 8vo, 1843).

While employed on the Irish survey, Portlock assisted in the advance of various scientific institutions in Ireland. In 1831 the Geological Society was formed, and the Zoological and other scientific societies rapidly followed. Portlock was one of the early presidents of both the Geological and Zoological Societies, and contributed to the former twenty papers, including presidential addresses, in 1838 and 1839. He was again president of the Geological Society in 1851 and 1852. In 1835 the British Association met in Dublin, and Portlock was a member of the local committee and secretary of the section of geology and geography. He was president of the geological section at Belfast in 1852. In the ‘Proceedings of the Royal Irish Academy’ for 1837 his name appears in a