46 SCIENCE 
seated in a stationary railway coach when a 
train on an adjoining track moves forward. 
It would be more strictly comparable with the 
effect produced by two trains, one on each 
side of the stationary coach, moving forward 
at the same speed. 
When this optical illusion receives due pub- 
licity in courses in physics, physiology and 
physical culture in our colleges, schools and 
gymnasia, there will be less danger attendent 
upon open-water swimming for tank-, pond- 
and river-trained> swimmers who venture be- 
yond their depths in larger bodies of water. 
And less danger will mean less loss of life. 
It will be obvious to the reader that a 
swimmer should choose fixed objects by which 
to gauge his progress. But this is not the 
place for a discussion of the choice and use of 
such objects. 
Water R. SHaw 
UNIVERSITY OF THE PHILIPPINES, 
Maniua, P. I. 
SCIENTIFIC BOOKS 
Flora of Bermuda. By NatHantet Lorp Brit- 
ton. New York, Charles Scribner’s Sons, 
1918. Pp. xi+ 585. Illustrated. Price $4.50. 
The geographic location of the islands form- 
ing the Bermuda archipelago, distant 666 naut- 
ical miles from Sandy Hook, 700 miles from 
Charleston, South Carolina, 736 nautical miles 
to Halifax and the island of St. Thomas 800 
miles away, makes their flora of unusual 
botanic interest. Within two days’ easy sail- 
ing distance from New York, the Bermudas 
have been favored by American tourists, who, 
leaying the rigors of a northern winter be- 
hind, step off upon land with a subtropic cli- 
mate. No adequate account of the interesting 
flora has been available to the ordinary trav- 
eler interested in the native and garden plants 
of the islands. A number of lists have been 
published from time to time, but these are in- 
accessible and mostly out of print. The most 
noteworthy of these publications, useful for 
the identification of the plants, are the “ Chal- 
lenger Report on the Botany of Bermudas” 
(1884), by W. B. Hemsley; “The Botany of 
Bermuda” (1884), by J. H. Lefroy and 
[N. 8. Vou. XLVIII. No. 1228 
“Plants of the Bermudas or Somers’ Islands ” 
(1885), by O. A. Reade. The want of a com- 
pendium of the flora of the Bermudas has long 
been a desideratum. The reviewer felt this 
lack very keenly on a botanic expedition to the 
islands in the summer of 1905 for the purpose 
of ecologic investigation. The plants collected 
there were named by the use of the Challenger 
Report, which he found incomplete and un- 
satisfying. 
Dr. Britton, after a number of visits to the 
islands, where he had been ably assisted by 
Mrs. Britton and Mr. Stewardson Brown, has 
at last published the results of his field, her- 
barium and literary studies of the Bermuda 
flora. He acknowledges the assistance of na- 
tive Bermudians, as also American botanists, 
who have elaborated special groups of plants. 
The Flora of Bermuda is a book attractively 
bound in a purple binding, representing the 
accurately matched color of Bermudiana, 
Sisyrinchium Bermudiana U., the Bermuda 
blue-eyed grass, which also appears as the 
frontispiece. The typography of the book 
leaves little to be desired and the illustrations, 
which represent line drawings of the principal 
species, will enable the botanically uninitiated 
to determine the plants, which are native and 
introduced. A useful bibliography is a fea- 
ture of the book and the index comprises both 
common and scientific names. Much interest- 
ing information, not usually incorporated in 
manuals of botany, is included, and rightly 
so. We read, for example, on page 71 under 
LInlium longiflorum Thunb., that the “ Haster 
Lily, White Japanese Lily, is extensively grown 
for export in a race (L. Harristz Carr,) some- 
times said to have originated here, but this 
industry is not as important as it was some 
years ago, although the Lily fields are yet a 
very conspicuous feature in the spring. The 
industry commenced about 1878 and reached 
its greatest development from 1890 to 1903.” 
The research of Dr. Britton and his associates 
has enlarged considerably our knowledge of the 
botanie geography of the group. The native 
plants of Bermuda have originated from seeds, 
or othe» parts, brought from the American 
mainland, or the West Indies, by the natural 
