illumination intensity, cooling unit, diapositive center 
ing device, and reduction printer. Operating at a 
nominal projection distance of 525 mm. the Balplex 
Plotter is excellent for medium and large scale mapp 
ing. Freedom from mechanical linkages prevents 
disturbing calibration. No new techniques need be 
learned. Time tested Multiplex principles of adjusting 
swing, tilt, and tip are used. Maintenance costs are 
minimized. 
Activities and Products 
Bausch & Lomb Optical Company with main factories 
at Rochester, New York, U. S. A. has been engaged in 
the production of optical products for 103 years. They 
are completely integrated optical manufacturers pro 
ducing their own glass and metal parts. Sales are 
directed through a large domestic distribution organi 
zation and a separate Export Division with head 
quarters in Rochester. Bausch & Lomb products con 
sist of a complete line of microscopes, projection in 
struments, refractometers, monochromators, metallo- 
graphs, spectrographs, photogrammetric instruments, 
binoculars, CinemaScope, Baltar, Cinephor lenses, and 
other scientific instruments, as well as ophthalmic len 
ses, frames, and mountings, and the famous Ray-Ban 
Sun Glasses. 
Swedish Representative 
Aga Bausch & Lomb AB, 
Malmskillnadsgatan 39 v , Stockholm 
6. Hilger & Watts Limited, Watts Division. 
98 St. Paneras Way, Camden Road, London N.W.l. 
England 
Representatives 
V. Towns 
Professor E. H. Thompson 
J. A. Armstrong 
Exhibit 
Hilger & Watts Ltd. are displaying: 
The Thompson-Watts Plotter for accurate mapping 
from air photographs to all scales and for aerial tri 
angulation. 
Radial Line Plotter — a simple, accurate and inexpen 
sive instrument for transferring planimetrie details of 
aerial photographs directly onto the map base. 
Microptic Theodolites reading directly to one second 
and twenty seconds. 
Levels — a precision level for working to the highest 
order of accuracy, and other general purpose. Levels 
for surveying. 
Beacon Lamp — new type of light-weight lamp. 
The Ewing Stadi-Altimeter — a theodolite attachment 
for direct reading tacheometry. 
Tacheometer Prism and Staff, for accurate tacheo 
metrie work. 
21 
Activities and Products 
Hilger & Watts Ltd. have been making scientific in 
struments since 1857 and can justly claim to have 
maintained a consistently high standard of research, 
development, and precision craftsmanship. 
In addition to the instruments shown at this exhibi 
tion, the firm makes a full range of equipment and 
instruments for surveying, including seismographs and 
variometers for geophysical prospecting. 
Of special interest at this Congress is the Thompson- 
Watts Plotter, which is based on original principles and 
is characterized by compactness and simplicity of 
operation. 
Swedish Representative 
Firma Labora, Birger Jarlsgatan 119, Stockholm Va. 
7. Kern & Co., Ltd. 
Aarau, Switzerland 
Representatives 
H. Wild 
R. Conzett 
H. Yzerman 
Exhibit 
Geodetic and topographical instruments: 
Theodolites 
Tacheometers 
Levelling instruments 
Plane-table equipments 
Activities and Products 
Manufacture of precision lenses 
Manufacture of precision instruments and optical in 
struments 
Development of photogrammetric precision plotting 
machines 
Swedish Representative 
Merkur, Instrument AB, 
Hollandargatan 8, Stockholm 3 
8, 10. VEB Carl Zeiss Jena. 
Jena, Germany 
Representatives 
E. Feldkeller 
J. Rost 
H. Schrumpf 
Exhibit 
I. Photogrammetry 
Terrestrial: 
Phototheodolite f = 19 cm., plates 13 X 18 cm. 
Stereo comparator for point-by-point evaluation of 
photograms up to 18x18 cm.