NovEMBER 1, 1918] 
explanation of this phenomenon. The theory 
then put forward attributes the ascent of the 
sap to transpiration from leaves of the tree and 
the tensile strength or cohesion of the fluid 
in its capillary tubes. 
Another matter of very great general interest 
was dealt with by Joly when he determined the 
age of the ocean by estimating the amount of 
common salt carried to it by the rivers and 
calculating the length of time that must have 
elapsed in order that the salt in sea water 
should have acquired its present concentration. 
Sections of various kinds of rock show re- 
markable little rainbow-colored circles. Joly 
was the first to prove that these rainbow-like 
circles or pleo-chroic haloes, occur about par- 
ticles of salts of the rare metals uranium and 
thorium; metals which are always undergoing 
decomposition into elements of lower atomic 
weight. The haloes are due to the bombard- 
ment of the substance of the rock by the radio- 
active particles discharged from the heavy ele- 
ments. The rate of transformation of uranium 
and thorium into these radio-active substances 
being known, it has been possible to calculate 
the length of time necessary for the formation 
of the haloes and therefore the age of the rocks. 
Joly has been a pioneer in the applications of 
radio-activity to geological phenomena, e. g., 
the origin of mountain ranges. 
The late Professor Lowell’s book on Mars led 
Jolly to offer a relatively simple explanation of 
the canals of Schiaparelli. He attributed them 
to the gravitational effects of small satellites 
falling into the planet. 
Even biological problems have engaged the 
versatile professor’s attention. In a book en- 
titled “ The Abundance of Life” he submits a 
dynamic basis for evolution. 
His interest in radio-activity led him at an 
early date to suggest the insertion of radium 
into cancers, and recently—in conjunction 
with Captain William Stevenson, R.A.M.C.— 
he suggested the use of emanation needles, 
which he invented, for therapeutic purposes. 
Joly has for many years been a keen yachts- 
man, and recently has devoted much time to 
problems connected with submarine warfare. 
He has suggested many applications of modern 
SCIENCE 
437 
science to navigation, and especially those de- 
pendent upon the principles of synchronous 
signalling. 
In his own university Professor Joly is 
known as a reformer, being largely responsible 
for various recent changes. He became secre- 
tary to the Academic Council on the death of 
Professor Edward Dowden, the Shakespearean 
scholar. 
During the rebellion in 1915 he took an ac- 
tive part in the defense of the college. An ac- 
count from his pen of this episode appeared in 
Blackwood’s Magazine. He is a commissioner 
of Irish Lights. He is warden of the Alex- 
andra College for Women. For many years he 
has been secretary of the Royal Dublin Society. 
He is a fellow of the Royal Society. In 1910 
he received from the society a royal medal. In 
1911 he received a royal medal from the Royal 
Dublin Society. 
Among his many publications are to be noted 
— Radio-activity and Geology,” “ Synchron- 
ous Signalling in Navigation,’ “The Birth- 
time of the World,” and a vast number of con- 
tributions to various scientific journals, no- 
tably to the Philosophical Magazine, of which 
he has been one of the editors for many years. 
WILLIAM JOHN KEEP 
Wituiam Joun Keep, consulting engineer 
for the Michigan Stove Company, manufac- 
turer of testing machines and writer on foun- 
dry topics, died on September 30. He was 
born in 1842, at Oberlin, Ohio, and studied at 
Oberlin and at Union College, where he was 
graduated in 1865 with the degree of civil 
engineer. For several years during his resi- 
dence in Troy he gave a course of lectures on 
the steam engine to the senior class of the 
Rensselaer Polytechnic Institute. 
During all his life Mr. Keep was very 
much interested in experimental tests with 
east iron and other metals. In 1885 he dis- 
covered the relation between the shrinkage 
and chemical composition of cast iron and de- 
vised the systems of “ Keep’s Test,” which he 
later named “ Mechanical Analysis.” This is 
used largely in the United States and other 
countries instead of chemical analysis. His 
