R. Bean: Instrumenta 
tion for the integrated 
photogrammetric 
system of U.S. G.S. 
(Publ. IIB 1) 
special endowments of practicality, stability and accuracy, that distinguish 
this instrument from other plotters based on the same principle. 
He then describes the practical benefits deriving from the application of new 
electro-magnetic devices invented by him and which are fitted to all his plotters 
putting emphasis upon their simplicity, accuracy and reliability. 
After having expressed his opinion on the advantages accruing to the instru 
mental realizations deriving from the application of principles that do not 
require excessive mechanical and optical enslavement and after having pointed 
out the test methods to ascertain the accuracy of the plotters, he concludes by 
affirming that photogrammetry can supply such accurate topographic maps that 
they are more than sufficient for the practical employ in all engineering and 
cadastral survey uses and that the high cost of the work due to too costly and too 
delicate-to-use instruments damages the progress of the photogrammetrical 
industry and therefore it is necessary that technicians and inventors of photo 
grammetrical instruments should always keep in mind that photogrammetry is, 
above all, an applied science. 
Principes théoriques et de construction à la base des plus récents appareils de 
restitution photogrammétriques O.M.I. Nistri 
L’auteur commence par citer les nombreux articles apparus dans des Revues italiennes et 
étrangères pour l’illustration des principes évolutifs de ses idées dans la réalisation des appareils 
de restitution photogrammétrique qui portent son nom. 
Malgré sa prédilection pour le principe de la projection optique directe, de grande simplicité, 
et sur lequel ont été construits ses premiers appareils de restitution et le Multiplo, dont il a la 
priorité, il n’a pas manqué de s’occuper, en même temps, de la restitution à vision binoculaire 
stéréoscopique, comme en fait foi son premier Fotostereografo Mod. Alpha, présenté au IV Congrès 
International de Photogrammétrie à Paris, en 1934. 
L’auteur parle ensuite des bénéfices réalisés avec le Fotostereografo Mod. Beta présenté à ce 
Congrès et des avantages obtenus, en remplaçant, sur tous ses appareils de restitution, les 
transmissions mécaniques par des dispositifs électro-magnétiques. 
Il conclue en exprimant son avis sur la nécessité que les réalisations instrumentales simplifient 
au lieu d’aggraver les servitudes mécaniques et optiques et cela en vue de favoriser ces principes 
d’économie qui seuls pourront contribuer à une diffusion plus étendue des méthodes photo 
grammétriques, pour le levé du terrain. 
La parole est donnée à M. R. Bean, Etats-Unis, pour son exposé sur »Instru 
mentation for the integrated photogrammetric system of the U.S. Geological 
Survey». Résumé: 
The integrated photogrammetric system now being placed in operation by 
the Geological Survey is the result of coordinated research in aerial photography, 
photogrammetric instruments, and techniques and standards. 
A major aim of the new system is to exploit the inherent advantages of twin 
iow-oblique photography. This became practicable with the development of the 
Twinplex instrument for horizontal and vertical aerotriangulation using twin 
low-oblique photography. Accompanying this major development, a whole 
series of related improvements in equipment and techniques has been incorpo 
rated into the Geological Survey system. 
To improve the photographic and geometric qualities of aerial photography, 
new cameras (T-12) having improved mechanical characteristics and equipped 
with high-resolution, low-distortion lenses (Planigon) are in use. 
A unique multi-collimator camera calibrator, by means of which cameras can 
be quickly and carefully tested, by stereoscopic measurement of test plates, has 
been installed. 
A newly developed twin-camera mount, incorporating a center-of-gravity 
suspension, provides for maximum resolution of the twin photography by 
minimizing the effect of angular vibrations and accelerations. 
ER-55 projectors, designed to be used with either vertical or oblique photogra 
phy, can be used in pairs as compilation instruments, in multiple arrangements 
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