XV 



hill and station, at distances averaging a mile asunder ; and on this the 

 minor levelling of the detail survey depended. This also was ultimately 

 generalized into a system by Lieut. Portlock, and by him furnished regu- 

 larly and rapidly. In fulfilling this purpose, he personally carried a line 

 of levelling across the island from the coast of Down to the coast of 

 Donegal, and caused several lines to be observed in other places. In this 

 way a more general and homogeneous system of altitudes was obtained 

 than had ever before been attempted. It supplied the data for the paper 

 on Tides by the Astronomer Royal, published in the ' Philosophical 

 Transactions.' 



In all this we see a character conspicuous alike for ability and energetic 

 perseverance ; but among its other elements, there was one which may be 

 properly noticed here the praiseworthy example he set to the men under 

 his command. They felt that with him they were in the hands of some- 

 thing superior to themselves in intellect and acquirements, and they im- 

 proved in a marked degree in the duties of the survey, in intelligence, and 

 the habit of obedience. " They needed only encouragement, no coercion, 

 and they rapidly acquired knowledge ; to all of which I can testify," 

 writes one of Portlock' s brother officers ; " and I am sure it is the expe- 

 rience of the whole corps, more perhaps than any other in the army, that 

 when officers study the characters of their men, and use in governing them 

 the knowledge so acquired, they are amply rewarded by the result, and 

 need no coarser discipline." Sergeant Manning, who worked under Lieut. 

 Portlock through the whole period of his service on the Irish survey, was 

 chosen as the non-commissioned officer best fitted to take charge of a party 

 sent in 1848 to the Cape of Good Hope, to verify, under direction of Mr. 

 (now Sir Thomas) Maclear, the base measured by Lacaille nearly a century 

 before. 



Of the great value of the Irish survey in connexion with the geology, 

 archaeology, statistics, and industrial resources of Ireland, this is not the 

 place to speak. Suffice it to say that when the time came for drawing up a 

 Report on the subject, Lieut. Portlock proved himself not less able as a 

 geological than as a geodetical observer. His separate Report on the 

 Geology of Londonderry has been pronounced by high authority to be " a 

 perfect model for fidelity of observation and minute attention to pheno- 

 mena." It is safe to affirm that the name of Portlock will ever be most 

 honourably associated with the history of the Ordnance Survey of Ireland. 



In 1843 Captain Portlock was ordered to Corfu on the ordinary duties 

 of his corps. In the comparative leisure which he then enjoyed he wrote 

 papers on the geology and natural history of the island, and on professional 

 subjects. Some of these were published in the Reports of the British 

 Association, the Annals of Natural History, and Journal of the Geological 

 Society. The Association voted him a grant " for the Exploration of the 

 Marine Zoology of Corfu," the results of which he embodied in two papers 

 subsequently published. In these again we have evidence of his activity 

 of mind and accuracy of observation. 



