656 
country. Mr. Thomas A. Edison was 
among the distinguished electricians pres- 
ent, while a great number of colleges were 
represented by exhibitors and guests, Vas- 
sar sending a contingent of a dozen students 
interested in natural science. 
Dr. Michael I. Pupin exhibited the 
original apparatus used in developing the 
recent invention for the improvement of 
long-distance land and ocean telephony 
which has recently been bought by the 
American Telephone Company. Mr. Peter 
Cooper Hewitt showed numerous samples 
of his recently invented high efficiency 
lamps. In these lamps mercury vapor is 
used instead of a filament, the lamp consist- 
ing of a long, cylindrical glass tube. At 
the bottom of each is some mercury, from 
which, when the current of electricity has 
passed through it, issues the vapor and a 
most peculiar colored lightis emitted. It 
is half purple, half green. This is a dis- 
advantage, but it can be obviated by the use 
of counteracting colored shades. In aroom 
near the Hewitt lights were the akouphone 
and akoulalion invented by Mr. M. R. 
Hutchison. They are microtelephonic in- 
struments, so constructed as to reproduce 
and intensify sounds and still preserve their 
quality, and many successful experiments 
were made upon deaf mutes, in which they 
were taught many new words during the 
evening. One of the largest lecture rooms 
of the university had been set aside for the 
use of Mr. Nicola Tesla, where he showed 
numerous interesting experiments with 
high-frequency currents. 
Much interest was shown in the exhibit 
of European Nernst lamps, made by Mr. 
William J. Hammer, who also showed 
Weldemar Paulsen’s new telephonograph 
and telegraphone, loaned by Lemvig Fog 
and Emil 8. Hagemann of Copenhagen, 
Denmark. 
These instruments receive telephone mes- 
sages in the absence of the recipient and 
SCIENCE. 
[N.S. Vou. XIII. No. 330. 
record them on a kind of magnetic phono- 
graph, which repeats them when the one 
for whom they are intended returns. 
Another exhibit of Mr. Hammer’s was a 
collection of aéronautical pictures, compris- 
ing photographs of Professor §. P. Langley’s 
aerodrome, Sir Hiram §. Maxim’s flying 
machine, Santos-Dumont’s dirigible air- 
ship, and Count Zeppelin’s balloon; to- 
gether with the balloon tests made during 
the Aéronautical Congress, at the Paris 
Exposition of 1900, and by the Aéro Club 
of France. Most of these photographs were 
taken by the exhibitor. Prof. S. P. Lang- 
ley exhibited his latest form of bolometer for 
spectrum analysis and showed many draw- 
ings and diagrams of the principles and 
results obtained. 
Professor W. 8. Franklin exhibited a mag- 
nesia are lamp, an electrolytic lamp on the 
Nernst principle, operating on 1,000 volts. 
Professor Francis C. Crocker showed mag- 
netic liquids, with apparatus in operation for 
showing the magnetic properties of liquids 
and for measuring their permeability, and 
Mr. Martin P. Rice, anew X-ray appara- 
tus employing a modified form of Wehnelt 
interrupter. Radiographing of alternating 
currents was shown in a large room which 
could be darkened at will. The exhibitors 
were Professor Harris J. Ryan and Professor 
J. O. Phelon, and their method secured 
stationary and continuous diagrams of alter- 
nating current values by records made from 
the radiographs of a rapidly rotating cath- 
ode ray, the rotation being caused by the 
action of the current. 
Professor Elihu Thomson had a most in- 
teresting exhibit consisting of a dynamo 
static machine and a new rotary electrical 
apparatus. The former contained a small 
direct-current motor, the windings of which 
were tapped and connected to two rings, 
giving a primary alternating current for the 
operation of a step-up transformer which 
gave a secondary current of about 20,000 
