January 18, 1917 | 
“MORTALITY TABLES AND EXPECTATION 
OF LIFE. 
— Nature of July 6 (xcvii., pp. 383-384) 
reference was made to a statement by Dr. 
W. W. Campbell, president of the American Asso- 
ciation for the Advancement of Science, that recent 
discoveries in preventive and curative medicine 
had increased the average length of life by many 
years, and that the increase so caused had been 
great for those healthy men whose lives had been 
accepted as risks to be insured by life assurance 
companies. While it was admitted that there was 
a high probability in favour of that conclusion, 
it was also pointed out that the tables in existing 
use had been available for fifteen years only, and 
that the time had not come for them to be super- 
sseded by fresh observations. Upon this Dr. Camp- 
bell stated in Nature of September 21 (p. 48) that 
the data upon which those tables are founded go 
back to the thirty years from 1863 to 1893, and 
do not therefore give full effect to the improve- 
ment in the duration of life which he believes has 
arisen during the last fifty years. 
Observations recently made in America and in 
Australia have raised questions as to this alleged 
improvement which call for careful consideration. 
‘They affect principally the middle-aged man—that 
is, the man of forty years or more. They do not, 
therefore, directly negative Dr. Campbell’s con- 
clusion, which relates to persons under that age 
as well as to some above it. Dr. C. F. Bolduan, 
who is director of the Bureau of Public Health 
Education in New York, is quoted in the Lancet 
and the Times as having stated in an official 
report that the death-rate in the United States 
‘registration area at the age period forty-five to 
fifty-four has increased by nearly 2 per cent. 
-during the last ten years, and that between fifty- 
five and sixty-four by nearly 7 per cent. When 
these figures are compared with those representing 
the variation in death-rates between 1850 and 
goo, as given in Mr. Gore’s report to the New 
York International Congress of Actuaries, they 
acquire some significance. That report records 
for ages forty to forty-nine a diminution in the 
rate of mortality of 7} per cent., for fifty to fifty- 
‘nine of 7% per cent., and for sixty to sixty-nine 
of 61 per cent. If it is the fact that this favour- 
able tendency has been checked at a time when 
not only the discoveries referred to by Dr. Camp- 
bell, but other contributory causes, such as better 
sanitation, have been in full operation and should 
have produced a further diminution in the rate of 
mortality, it is evident that some adverse influences 
are at work which ought to be investigated. Dr. 
Bolduan finds them in over-strain and over-eating, 
and a committee appointed by the Department 
of Trade of the Commonwealth of Australia to in- 
quire into the causes of death and invalidity has 
made a report on the risks of middle age which 
arrives at similar conclusions. 
Whether a like reaction is observable in this 
country may be doubted. The report of Mr. 
Warner to the actuarial congress mentioned above 
showed that, as between the investigation of the 
NO. 2464, VOL. 98] 
NATURE 
59! 
Institute of Actuaries ending in 1863 (termed H™) 
and that of the Assurance Companies ending in 
1893 (termed O™), the expectation of life for 
males uniformly increased—at age forty from 27°4 
years to 27'9; at age fifty from 20°3 to 206; at 
age sixty from 139 to.14°1; at age seventy from 
8°5 to 87. It is unfortunate that the body of 
experience available relating to female mortality 
is insufficient for a similar comparison to be made, 
for there is reason to think that female life is now 
passed in better hygienic conditions than 
formerly. 
The remedy suggested in America and Australia 
consists in a campaign against avoidable adult 
mortality; but there is some force in the caution 
of the Lancet that risk lies in the direction of 
faddiness. 
‘PROF. THOMAS PURDIE, F.R.S. 
"THE value of a close, sympathetic relationship 
between professor and student is perhaps not 
fully recognised, and certainly can be properly 
appreciated only when it has formed part of a 
personal experience. The power of winning the 
affection and confidence of young men was a 
marked feature of the personality of Prof. Purdie, 
whose death was announced in Nature of Decem- 
ber 21 last; and no record of his life, however 
slight, would be complete without special reference 
to the wonderful insight and understanding that 
bound him to his students. During the twenty- 
five years he occupied the chair of chemistry in 
St. Andrews he devoted himself to the develop- 
ment of character in the undergraduate quite as 
much as to the simpler duty of converting him 
into a chemist. 
Purdie’s early experience in life enabled him to 
escape the limitations frequently imposed on the 
specialist. Born at Biggar in 1843, he spent seven 
years of his youth in South America, where, under 
conditions which were always primitive and often 
dangerous, he lived an active, open-air life. All 
his time, however, was not spent in the saddle. 
The flora of the pampas and the minerals of the 
hills .claimed his attention and interest, and 
aroused the spirit of inquiry which was never 
thereafter quenched. On his return to this 
country at the age of twenty-seven, definite direc- 
tion was given to these scientific instincts by a 
conversation with Huxley while walking under 
the cliffs at St. Andrews, and probably to this 
impetus can be traced his subsequent career as a 
chemist. 
After studying at the Royal School of Mines 
under Frankland, he went to Wirzburg, where 
he came under the inspiring influence of Wis- 
licenus, and a close and lasting friendship sprang 
up between the two men, who had much in 
common. His teaching experience was gained at 
South Kensington and Newcastle-under-Lyme, and 
in 1884 he was appointed to the vacant chair at 
St. Andrews. The University must for all time 
be grateful to the electors for their choice. 
Cramped accommodation, imperfect equipment, 
| and the fact that chemistry had then no official 
