Renseignements généraux

Nº de série

S/O

Nº de partie

3

Nombre total de parties

4

Ou

S/O

Brevets

S/O

Description générale

Grey metal box houses electrical components; black and goldtone mounted synthetic faceplate on box; black mounted synthetic knob; black rubber (?) covering on 2 electrical cables extending from box: metal plug fitted to end of one cable; metal and synthetic connector fitted to other cable.

Dimensions

Remarque : Cette information reflète la taille générale pour l’entreposage et ne représente pas nécessairement les véritables dimensions de l’objet.

Longueur

73,0 cm

Largeur

46,0 cm

Hauteur

8,5 cm

Épaisseur

S/O

Poids

S/O

Diamètre

S/O

Volume

S/O

Lexique

Groupe

Exploration et levé

Catégorie

Photogrammétrie

Sous-catégorie

S/O

Fabricant

Ou

Inconnu

Pays

Inconnu

État/province

Inconnu

Ville

Inconnu

Contexte

Pays

Canada

État/province

Québec

Période

Instrument used 1946- August, 2003.

Canada

Projector used by Canadian International Paper from 1946 until August 2003 in the Forest Engineering Department. The instrument was installed on the second floor of the rear building in Maniwaki, Québec [see photos attached, and in Supp. Info.]. The projector was assembled on site. The purchase cost was $ 1 791 (US) in 1946. E.B. Eddy, another important Canadian lumber company, was also using a similar type of equipment in Hull in 1946. Canadian International Paper Co. was a subsidiary of International Paper Co. founded in 1898 in Albany, New York. The Canadian subsidiary was originally formed in 1919 as the St. Maurice Lumber Company but was renamed in 1925 as the Canadian International Paper Co. It acquired vast timberland territories in Canada and constructed some of the world's largest newsprint mills in Québec province. The company was sold to Canadian Pacific Forest Products in 1989 which became Avenor Inc. in 1994. In 1998, Avenor was bought by Bowater. It was important for lumber companies to know the forest resources of their land. Aerial photography was found to be helpful for inventorying those resources in Canada, particularly near the end of the Second World War. The National Research Council played a role in designing a camera. For the aerial photography service, CIP was dealing with Spartan Air Services Limited, located in Ottawa and also Capital Air Surveys Ltd. [Ref. 1]

Fonction

Possibly used to start projector lamps, and control their intensity.

Technique

The P-4141 projects images of opaque objects like photographic prints, artwork or maps onto a tracing table. The opaque original is placed vertically in a copy holder on the side of the lamp house, which is mounted at the top of the projector above the projection lens and tracing table. Inside the lamp house, two 500 watt lights illuminate the image, which is reflected downward by a diagonal mirror mounted at 45 degrees to the image and to the optical axis of the lens. This reflected light from the image passes down through the projection lens onto the surface of the tracing table. The operator adjusts the focus and magnification of the image by moving the lamp house up and down, with the aid of a motor-activated chain drive, or moving the lens along its axis. The operator can align the image horizontally on the tracing table by shifting the lamp house back and forth by up to 16 inches. The operator produces a forest inventory map in the following way, First, he/she projects a published base map onto the table, adjusts magnification to render the desired scale, and traces the relevant planimetric data (roads, rivers, lakes, etc.) onto the blank map sheet. Then, he/she places the aerial photo for the map in the copy holder, adjusts magnification to fit the new base map (and corrects for tilt if the tracing table is adjustable) and traces the various forest stand boundaries, which have previously been outlined on the photo by an air photo interpreter. The mirror stereoscope [2009.0070] is used to analyse the aerial photographs. Using two properly oriented photographs, it provides the mental impression of a three-dimensional model. It enables the viewer to have a clearer image and be able to estimate relative heights of objects, in this case, trees. Before aerial photography, forest resources inventories were done by field sampling on the ground. This method is still being used as it gives a detailed tree and stand information. This method of transferring data from aerial photographs was imprecise but was the only one available at the time and was used in the forestry industry until about 1990-1995. It was followed by a process known as "orthographie" in which paper photos were scanned, then corrected in order to be transposed on the 3-D land digital model they had. This process lasted only a few years to be followed by the use of digital aerial photographs which were converted to 3-D by computer software and corrected directly in their 3-D map model. This model is much more exact and is nowadays used everywhere.

Notes sur la région

Inconnu

Détails

Marques

None evident.

Manque

Unknown.

Fini

Grey metal box houses electrical components; black and goldtone mounted synthetic faceplate on box; black mounted synthetic knob; black rubber (?) covering on 2 electrical cables extending from box: metal plug fitted to end of one cable; metal and synthetic connector fitted to other cable.

Décoration

S/O