Henry Hennessy. 141 



weights and measures, based upon the length of the earth's polar 

 axis, a quantity which is capable of more accurate determination 

 than the earth's quadrant. Standards, such as the polar foot and 

 the polar pound, with a complete series of weights and measures on 

 the polar system, are contained in the Museum of the Royal College 

 of Science, Dublin. There are also, in the same collection, many 

 ingenious models and inventions designed by Professor Hennessy to 

 illustrate various principles, chiefly in mechanism, but also in 

 matters touching civil engineering, such as, for instance, the form 

 and structure of sewers best adapted to the purpose of obtaining the 

 greatest scour, with due provision for a great influx of storm water. 

 {" Hydraulic Problems on the Cross-sections of Pipes and Channels." 

 'Proc./ 1888.) There are also models illustrating the geometrical 

 construction of the cell of the honey bee, which was the subject of 

 three short communications published in the " Proceedings," 1885 

 to 1887. 



In 1855, on the invitation of Cardinal Xewman, he accepted 

 the appointment of Professor of Physics in the Roman Catholic 

 University of Ireland, and, in 1874, he became the Professor of Applied 

 Mathematics in the Royal College of Science. 



On several occasions he delivered admirable addresses and lectures 

 on university education in its relation to the study of science as a 

 branch of human knowledge, as well also in its applications to the 

 Arts and Manufactures, or what is now generally known as Technical 

 Education. On this subject his opinions were thoroughly sound, and 

 worthy of much greater respect and attention than they actually 

 received at that time. To those who personally evinced an interest 

 in his work he was always pleased to explain his views, and the use 

 of his models. This he did with much lucidity and a remarkable 

 modesty of manner. The writer cannot easily forget the feeling of 

 admiration he experienced for his literary ability when, at a meeting, 

 now many years ago, a long official letter was read, and during the 

 progress of an ensuing discussion Professor Hennessy, on the instant, 

 wrote in detail a complete and lengthy reply, which, without erasure 

 or alteration of a single word, presented the views of himself and 

 colleagues so clearly and cogently that it was at once adopted. 



During the College Session of 1890-91 he was called on, under the 

 then recently-made Treasury rules applicable to clerical and adminis- 

 trative officials in the Civil Service, to retire from the Chair of 

 Applied Mathematics which he had filled] with such distinction, and, 

 as no intimation that such a course of action was intended had been 

 communicated to them, a great surprise fell upon some of his 

 colleagues when they became aware, during the Christmas vacation, 

 from persons wholly unconnected with the College, not only that he 



