November i8, 1897] 



NATURE 



55 



(2) N = u. o = I lo" - N = - I ; hence Z is a multiple 

 of II when a^ - «, + a^ _ a^ + a^ _ + ... jg a multiple of this 

 number. 



(3) N = 103. If we take o = 2,- we get io« - N = - 3, and 

 Z will be a multiple of 103 when 



K + loa,) - 3 (aj + ICW3) + 9 (a4 + loaj - 27 {a^ + loa-) 

 + 81 (flg + ICW9) - 37 (rtio + loa,i) + - ... 

 can be divided by 103 without residue. 



To take a numerical example, try if 298744898 is a multiple 

 of 103, and determine the residue if it is not. 



We get 



98 - 3 X 48 + 9 X 74 - 27 X 98 + 81 X 2 ^ - 1864 ; 19 X 103 



= 1957 ; therefore residue = 1957 - 1864 = 93, 

 wliich will be found correct by performing the division. 



I have no doubt the above rule will be well known to mathe- 

 maticians, but not being much acquainted with the theory of 

 numbers, I cannot at present tell where it may be found ; the 

 prooHs very easy. C. B5rgen. 



Wilhelmshaven, November 7. 



The examples given by Dr. Borgen, in his interesting com- 

 munication, fall under suggestions (2) and (6) in my second 

 letter, where if 5 = 7 the period ± i, 3, 2 may be used ; or if 

 8 = II the period + i is available ; or if 5 = 103 take 



5j = S - a = 103 - 3 

 giving the rule — 



Divide N into dual periods beginning from the units place ; 

 multiply each by (- «)'*, giving to n the successive values o, i, 

 2, 3 &c. ; the sum of these positive and negative products 

 is N,. 



I may add, this rule applies to S = 17, loi, 103, 107, 109, 

 taking a = - (2, i, 3, 7, 9), or to S = 19 if a = 5, but if 5 = 83, 

 N must be divided into triple periods, a being -f 4. 



Henry T. Burgess. 



Tarporley, West Norwood, November 11. 



HON. RALPH ABERCROMBY. 

 ■p ALPH ABERCROMBY was born in 1842, and was 

 -*-^ the youngest son of the third Lord Abercromby. 

 His mother was a daughter of Lord Medwyn, a Lord of 

 Session in Edinburgh. Several of his immediate relatives 

 had been eminently distinguished. His great-grand- 

 father, Sir Ralph Abercromby, who died in 1801, in the 

 moment of victory, at the Battle of Alexandria, had 

 served his country with brilliant distinction, in the West 

 Indies (Trinidad) and at the Helder. 



As soon as the news of Sir Ralph's death reached 

 England, and in commemoration of his services, a barony 

 was conferred upon his widow, with remainder to his 

 sons. 



Of these sons the second became Sir John. He was 

 in the service of the East India Company, and took the 

 Island of Mauritius in 18 10. .Another was Speaker of 

 the House of Commons in 1835, and was created Lord 

 Dunfermline. 



Ralph was never robust, even as a boy. He went to 

 Harrow, and soon was obliged, owing to delicacy, to leave 

 the school. He had, however, shown signs of great 

 promise by taking a double remove after his first term. 



In June i860 he was gazetted to the 60th Rifles, and 

 four years later obtained his lieutenancy and joined the 

 Fourth Battalion at Quebec. 



The War of Secession was then at its height. Aber- 

 cromby obtained leave and visited the scene of action. 

 He took with him letters to General Grant, and was well 

 received, but he did not happen to be present at any of 

 the great battles. 



At the beginning of i865 he entered the Staff College, 

 having passed in without "cramming," but his health 

 soon broke down there. Two visits to Kreuznach pro- 

 duced no benefit, and in 1869, to his great regret, he felt 

 himself obliged to give up his commission. 



In later years he twice was sent on a voyage round 

 the world, in hopes of restoration to health ; and it was 



NO. 1464, VOL. 57] 



in the beginning of 1890, at the commencement of a 

 third voyage to the Pacific, that he was taken ill at 

 Sydney — an illness which terminated fatally June 21, 1897. 

 He passed away quietly in his sleep. 



Abercromby had, from a very early period, paid much 

 attention to observational meteorology. In his " Seas 

 and Skies in many Latitudes," observations are recorded 

 which he must have made during his military service in 

 Canada. His name will live longest in connection with 

 the new classification of clouds which he, in conjunction 

 with Prof Hildebrandsson, of Upsala, proposed, and 

 which was adopted by a majority of votes at the Inter- 

 national Meteorological Conference of Paris in September 

 1896. 



His published books were : " Principles of Forecasting 

 by means of Weather Charts," 1885, published by 

 authority of the Meteorological Council ; " Weather, a 

 Popular Exposition of the Nature of Weather Changes," 

 1887 (International Scientific Series) ; "Seas and Skies 

 in many Latitudes," 1888. In addition he brought out 

 many papers which appeared in various journals and 

 periodicals, such as the Proceedings of the Royal Society, 

 \.h.& Journals of the Royal and of the Scottish Meteoro- 

 logical Societies, as well as in Nature, Good Words, &c. 



Fifteen papers are down to his name between 1873 

 and 1884 in the Royal Society Catalogue of Scientific 

 Literature. 



From his sick bed in Sydney he showed his great 

 interest in the advancement of the science by making 

 grants of money^for the production of essays on meteoro- 

 logical subjects. Three of these have been published : 

 " On Moving Anticyclones in the Southern Hemisphere," 

 " On Southerly Bursters," and " On Types of Australian 

 Weather." 



Abercromby retained to the very last the power of 

 making and keeping friends. This was in great measure 

 due to his loyal and affectionate nature, which neither 

 distance nor illness could impair. Those who were with 

 him during his last suffering months bear witness to the 

 patience and gentleness, which were as conspicuous 

 under the trials of severe pain as they had been when 

 he was in full possession of his faculties. 



His lot was indeed a hard one. He had first to bear 

 the heavy disappointment of enforced resignation of a 

 profession which he loved, and in which his prospects 

 seemed so brilliant, and then he had to sustain the strain 

 of more than twenty years of impaired and gradually 

 failing health. 



He leaves behind him the memory of a warm un- 

 selfish friend, cut off in a distant land, far from his kith 

 and kin. R. H. Scott. 



REV. SAMUEL HAUGHTON, M.D. 



THE announcement of the death of Dr. Haughton has 

 been received with the deepest regret in various 

 scientific circles, and by his numerous personal friends 

 and acquaintance attracted to him by his sturdy honesty, 

 unselfishness, and geniality of disposition. He was born 

 in Carlow in 1821. After a distinguished undergraduate 

 career in Trinity College, Dublin, he was elected Fellow 

 thereof in 1844. He held the Professorship of Geology 

 from 1 85 1 to 1 88 1, in which latter year he was co-opted 

 Senior Fellow of the College. He was admitted F.R.S. 

 in 1858. The Universities of Oxford, Cambridge, and 

 Edinburgh signified their appreciation of his merits by 

 conferring on him the honorary degrees of D.C.L. and 

 LL.D., respectively. Having taken the degree of M.D. 

 in his own University in 1862, he was made Registrar of 

 the Medical School there, and applied himself with his 

 usual energy and activity to the reorganisation of that 

 School ; thereby raising it to its present condition of 

 high efficiency. He was elected a Governor of Sir 

 Patrick Dun's Hospital, which is connected with the 



