November 7. 1918] 



NATURE 



189 



was the enigmatic encrusting organism obtained 

 by him in the neighbourhood oi Madeira, and 

 afterwards named Merlia normani, in his honour, 

 by Mr. K. Kirkpatrick. A third genus of remark- 

 able interest which we owe to his enthusiasm is 

 the parasitic Crustacean, Synagoga, belonging to 

 the Ascothoracica, a highly specialised and 

 degenerate subdivision of the Cirrip 



But it must be emphasised that Canon Norman 

 was much more than a describer of new sp 

 and a discoverer of interesting forms. His re- 

 searches have been of real value in enlarging our 

 knowledge of the marine fauna in general, and 

 few others have contributed more than he did to 

 the faunistic study of the sea. 



A- cine who for many years had the privilege 

 of his friendship 1 can speak with the most sincere 

 admiration of his genial character, his perfect 

 sincerity, and the high ideals by which he regu- 

 lated his life. Of his work as a parish priest I 

 am not competent to speak, but I believe that his 

 ministration- were very highly valued by those 

 who came under his influence. Canon Norman 

 was a man of altogether lovable type, and it 

 was impossible to be in his company without feel- 

 ing the better for it. These characteristics lasted 

 to the end of his life, during the closing years 

 of which he had borne the infirmities of serious 

 illness with an unclouded mind and a fine courage, 

 and without losing the qualities which endeared 

 him to his friends. Sidney F. Harmer. 



PROF. OLAUS HENRICI, F.R.S. 



OLAUS MAGNUS FRIEDRICH ERDMANN 

 HENRICI was born in the year 1840 at 

 Meldorf, on the west coast of Holstein. After 

 leaving the gymnasium at Meldorf at the age of 

 sixteen, he worked in some engineering works at 

 Flensburg. Thence at the age of nineteen he 

 went to the Karlsruhe Polytechnicum, where he 

 had the inestimable advantage of coming under 

 tlie influence of Clebsch, by whose advice he de- 

 voted himself entirely to the study of mathematics. 

 At the age of twenty-two he went to Heidelberg, 

 where he attended Hesse's lectures, and obtained 

 the degree of Ph.D. He then studied under Weier- 

 Strass and Kronecker in Berlin. After a short 

 time spent as Privatdozenl at Kiel, he came to 



■>(1 in (865. 



in years Henrici worked at engineering 



ms. During this time he published a little 



book on skeleton structures (now called pin-jointed 



;ures), and he supplemented his earnings by 

 giving private lesson;, to schoolboys. In 1870, 

 after a short time spent as assistant to Prof. Hirst 

 at University College, London, hi' succeeded him 

 in the professorship of pure mathematics, and re- 

 tained this position for ten years, when he ex- 

 changed it for the professorship of applied mathc- 

 matii s. In 1NS4 hi- left Universit) College for the 

 professorship of mechanics and mathematics at the 

 Central Technical College, where he entered on a 

 new held of work in the organisation of a labora- 

 tory of mechanics, which has been the model of 



NO. 2558, VOL. 102] 



many others, and has had an important influence 

 on the education of English engineers. In 191 1 

 Henrici retired to Chandler's Ford, in Hampshire, 

 • lure he died on August 10 last. 



Henrici was a fellow of the Royal Society, and 

 at one time a member of its council. He was 

 president of the London Mathematical Society for 

 two years, and chairman of Section A of the 

 British Association in 1883. In 1884 the University 

 of St. Andrews conferred upon him the honorary 

 degree of LL.D. He acted as examiner in the 

 University of London from 1875 to 1880, and in 

 this capacity made his influence felt on the intro- 

 duction of modern methods into the teaching of 

 geometry. In 1877 he married the daughter of the 

 late Rev. Dr. Kennedy and sister of Sir Alex- 

 ander Kennedy, who survives him. There was one 

 child of the marriage, Major E. O. Henrici, of 

 the Royal Engineers. 



Henrici was the author of mathematical paper- 

 published in Crclle's Journal and the Proceeding - 

 of the London Mathematical Society. He con- 

 tributed several articles to the " Encyclopaedia 

 Britannica," amongst which that on "Projective 

 Geometry " stands out as a model of lucidity and 

 form of expression. He wrote jointly with his 

 son a valuable memoir on the theory of measure- 

 ment by metal tapes and wires in catenary, which 

 made it possible to calculate distances on slopes 

 up to 1 in 3 to an accuracy of one in a million. 

 He was the author of a remarkable little book 

 on "Congruent Figures,'* in which his ideas of 

 the mode of treating elementary geometry are 

 expounded. It covers in a small compass most 

 of the ground of the first four books of Euclid's 

 "Elements." At one time he purposed to write 

 a sequel to it on "Similar Figures," but it would 

 appear from his address to Section A of the British 

 Association in 1883 that he failed to find a method 

 of treating this part of the subject which entirely- 

 satisfied him. 



The introduction into English teaching of the 

 methods of vector analysis greatly interested 

 Henrici, but of his ideas there remains in per- 

 manent form only what is published in the little 

 book on "Vectors and Rotors" written by his 

 assistant, Mr. G. C. Turner, from notes of his 

 lectures. It deals only with the elementary parts 

 of the subject. The matter contained in this book 

 was to form the earlier portion of a more elaborate 

 treatise. A great amount of manuscript has been 

 left by Henrici, and it is much to be desired that 

 someone will be found to go through it with care 

 and save what i- possible of his ideas. 



Henrici was greatly interested in the construc- 

 tion of models to illustrate his teaching. One of 

 these, made of rods, showed two confocal hyper- 

 boloids connected together so that they could be 

 deformed, always, however, remaining confocal. 

 Il had a remarkable history, which he gave in the 

 catalogue of the Exhibition of Mathematical 

 Models at Munich in 1892. 



Perhaps the most strikingly original piece of 

 work he did was the invention of the harmonic 

 analyser for representing the equation of a curve 



