54 



NATURE 



[September 9^ 1920 



This method of determining the number of elec- 

 trons in the atom is by far the most direct yet 

 devised, as the interpretation of the experiments 

 does not involve the rather difficult averaging- 

 necessary for the compound scattering produced 

 by the electrons. 



Now if we make a table of all the elements 

 arranged in order of atomic weights, as is done by 

 chemists for the study of the Periodic Law, and 

 if we number them in this order, starting with 

 hydrogen at i, helium at 2, and so on, as on p. 53, 

 it will be seen that the resulting numbers are 

 always in the neighbourhood of half the atomic 

 weight. The nuclear charge is by hypothesis some 

 multiple of the electronic charge, and by experi- 



ment is about half the atomic weight, and so we are 

 almost forced to suppose that the ordinal number of 

 an element in the table is the same as the number 

 of electronic charges on its nucleus. We do not 

 anticipate an exact correspondence throughout the 

 table, because there may be (and in fact are) 

 gaps in it which represent hitherto undiscovered 

 elements. But apart from this we arrive at the 

 conception of an atomic number for each element. 

 The atomic number of an element is defined as the 

 number of positive electronic charges carried by 

 its nucleus, or, which is the same thing, as the 

 number of electrons surrounding this nucleus. 



(To be continued.) 



Obituary. 



Canon C. H. W. Johns. 

 "DY the death of the Rev. C. H. W. Johns, 

 -L* Master of St. Catharine's College, Cam- 

 bridge, and Canon of Norwich, Assyriology has 

 lost another of its most prominent representatives 

 in this country. It was almost exactly a year after 

 the death of Prof. L. W. King that Canon Johns 

 passed away. He had been noted as an Assyrian 

 scholar for many years past ; held the post of 

 lecturer in Assyrian at his college of Queens', in 

 the University of Cambridge, for fourteen years ; 

 and preceded Prof. King as Assyrian reader at 

 King's College, London. These lectureships he 

 vacated on his appointment as Master of St. 

 Catharine's in 1909. The duties of the head of a 

 college in no way interfered with the continued 

 prosecution of his Assyrian studies, and to the last 

 Dr. Johns was at work on the cuneiform inscrip- 

 tions to which he had devoted a large part of his 

 life. He was an excellent decipherer of the tablets, 

 and had had much experience as a student of 

 Ashurbanipal's library in the British Museum, to 

 the officials of which, and especially to the late Prof. 

 King, he was always persona grata and a valued 

 colleague in science. His most notable publication 

 is probably his "Assyrian Deeds and Documents," 

 published in 1898 — a series of copies and transla- 

 tions of a large number of cuneiform legal and 

 other records preserved in the British Museum. He 

 also wrote on the famous legal code of Hammurabi, 

 delivered the Schweich Lectures on the relations 

 between the Laws of Babylonia and the Laws of 

 the Hebrew peoples, and contributed articles on 

 Mesopotamian law and history to various scientific 

 journals and dictionaries, notably to the " Encyclo- 

 paedia Biblica." His death is a great loss to the 

 scientific study of Mesopotamian archaeology. 



H. R. Hall. 



Prof. Adam Politzer, whose death has just 

 been announced from Vienna, was recognised in 

 all lands as the leading specialist of his time in 

 diseases of the ear. He was born in Hungary 

 on October i, 1835, and, taking his medical 

 degrees at the University of Vienna in 1859, went 



NO. 2654, VOL. 106] 



abroad to study the anatomy and diseases of the 

 ear, coming to London to work at the pathology 

 of the -ear under Mr. Joseph Toynbee, F.R.S. 

 Returning to Vienna, he quickly established him- 

 self as the leading exponent of the newest learn- 

 ing concerning the organ of hearing and its 

 defects, and his growing fame drew medical men 

 to Vienna from all parts of the civilised world. 

 The secret of his success was that he founded 

 his methods of treatment on a first-hand know- 

 ledge of the structure, action, and pathology of 

 all parts of the ear. He sought to give to the 

 practice of the aural surgeon a foundation on fact, 

 and not the least of his discoveries were made 

 in the fields of normal anatomy. 



The death of Sir Charles Lvall leaves a gap 

 in the ranks of the older school of Orientalists, 

 in which field he will be remembered rather than 

 as an eminent Indian administrator. Sir Charles 

 became a member of the Civil Service in the United 

 Provinces of Agra and Oudh in 1867, and, without 

 much experience of district work, he was absorbed 

 in the Provincial Secretariat, and then went to 

 Simla and Calcutta. Much of his service was 

 passed in Assam, of which province he became 

 Chief Commissioner. Transferred to the Central 

 Provinces, his training in administration failed to 

 prepare him for the emergency of the great famine 

 of 1897, and he was removed to the India Office 

 as Secretary of the Judicial and Public Depart- 

 ment. Here he was able to resume his work on 

 Indian languages, particularly Hindustani, and he 

 showed his profound knowledge of Arabic by 

 numerous translations of its poetic literature, 

 which he discussed in successive editions of 

 the "Encyclopaedia Britannica." Sir Charles Lvall 

 was a tower of strength to the Royal Asiatic 

 Society, of which he w'as vice-president, working 

 with Orientalists like James Kennedy and Vincent 

 A. Smith, both of whom recently died. His 

 services to literature were rewarded by several 

 ! honorary degrees, and by the coveted distinction 

 of fellowship of the British .Academy. 



