FEBRUARY 22, 1901. ] 
img the secondary treatment with a clear film. 
A picture started as a negative may be reversed 
by turning on the light, but the high lights are 
already dark and the shadows must then become 
dark in contrast with them. The whole picture 
will then be very dark. By this new process 
the second picture may be as perfect as if the 
original treatment had been properly started. 
THE directory of the Washington Academy of 
Sciences and affiliated societies for 1901, com- 
piled by Dr. Marcus Baker, and corrected to 
about January 10th, has been distributed to 
members. The membership of the societies, ex- 
cluding corresponding members in some cases, 
is 2,557 and the number of persons 2,013. The 
membership is distributed among the different 
societies as follows : 
Academy of Sciences .................:2..0008 291 
Anthropological Society............... 125 
Biological Society..............c...00. + eee 171 
C@hemicallSocitebynce-ct-e-cesess-ec-neeescen ene 121 
Entomological Society.............02-s2c0ee0 52 
National Geographic Society................ 1059 
Geological Society..........-......22:02006 wee 147 
Columbia Historical Society.... 
IMedicaliSoctetyeccsrsesseerscsen=cses meres: 
Philosophical Society...............:0.-00000 
THE American Metrological Society has is- 
sued a circular, primarily for distribution among 
members of Congress, entitled ‘A Few Reasons 
Why the Metric System of Weights and Meas- 
ures should be Adopted in the United States.’ 
It presents very clearly the great advantages of 
the metric system and should be widely circu- 
‘ lated. Copies can probably be obtained from 
the president of the Society, President T. C. 
Mendenhall, Worcester, Mass., or the secre- 
tary, Professor J. H. Gore, Columbian Univer- 
sity, Washington, D. C. 
Ir is proposed in Dundee to erect a granite 
monument over the grave of James Bowman 
Lindsay, in the Western Cemetery of the city. 
Nature calls attention to the fact that Lindsay 
was a remarkable man, whose memory should 
not be permitted to fade. He was born in 1799, 
and taught electricity, magnetism and other 
subjects in Dundee for many years, dying there 
about forty years ago. In 1834 he foresaw that 
“houses and towns will in a short time be 
lighted by electricity instead of gas, and ma- 
SCIENCE. 
319 
chinery will be worked by it instead of steam.’ 
This prediction was the result of his own obser- 
vations of effects produced by the electric cur- 
rent, and not merely imaginative suggestions. 
In 1854 Lindsay transmitted telegraphic signals 
through water electrically ; and when the Brit- 
ish Association visited Aberdeen in 1859, he 
demonstrated the success of his method by 
transmitting signals across the harbor. He 
also read a paper upon it, entitled, ‘Telegraph- 
ing without wires.’ 
Iv is stated in the Lancet that, in consequence 
of a movement which was started two years ago, 
a salmon hatchery for the river Tweed has just 
been erected. The hatchery, which is fitted 
with all the modern improvements, is situated 
at East Learmouth, about a mile from Coruhill- 
on-Tweed, on an excellent site which has been 
granted by Harl Grey. The management of 
the hatchery is under the supervision of Mr. F. 
J. Douglas, Springwood Park, Kelso, and Mr. 
George Grey of Millfield. The hatchery is a 
private undertaking with which the River 
Tweed Commissioners have no official con- 
nection, and the cost of which has been sub- 
scribed to by every river proprietor from Tor- 
woodlee to Tillmouth. The building is 48 feet 
long by 20 feet wide and seven feet high inside. 
It is fitted with 12 boxes capable of holding in 
all 18 grilles, so that the 12 boxes combined have 
a capacity for about 300,000 salmon ova. If 
the fry were hatched three times in a season 
the output would not fall far short of 1,000,000 
salmon fry. The water supply is carefully fil- 
tered before passing into the boxes. There isin 
the hatchery an impounding tank of 1,100 gal- 
lons capacity for keeping the salmon in after 
capture until they are ready for spawning. 
The young fry will be kept until they are six 
months old. For this purpose six ponds are to 
be constructed 40 feet long by eight feet wide 
by four feet deep. ‘here are those who think 
that fish-culture may play an important part 
from a medical point of view in the future. 
Tue Prussian Minister of Public Instruction 
has issued an order regulating. experiments in 
hospitals which is quoted by the London Times 
as follows: ‘‘I hereby call the attention of 
those who have the management of clinical and 
