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Photoalidade

Details

Artifact no.
1996.0170.001
Manufacturer
POCKLINGTON, THOMAS CO.
Manufacturer Location
Toronto, Ontario, Canada
Manufactured Date
Circa 1941 - 1945
Context Function
TO MEASURE HORIZONTAL & VERTICAL ANGLES FROM AN OBLIQUE PHOTOGRAPH. USED FOR HORIZONTAL & VERTICAL POINT SELECTION FROM HORIZONTAL PHOTOGRAPHS.
Context Technical
PHOTOALIDADE IS USED FOR PLOTTING LINES OF DIRECTION, AND MEASURING ANGLES TO SELECTED FEATURES ON OBLIQUE & TERRESTRIAL PHOTOGRAPHS (REF.2). IT WAS INTRODUCED IN 1937. WHEN PHOTOS ARE CORRECTLY ADJUSTED IN THE PHOTOALIDADE, OBSERVATIONS ARE TAKEN IN THE SAME MANNER AS WITH A PLANE TABLE & TELESCOPIC ALIDADE/ PRECISION IS CONSISTANT IN POSITION & ELEVATION WITH VALUES OBTAINED BY PLANE TABLE & TELESCOPIC ALIDADE, BUT RESULTS ARE OBTAINED MORE QUICKLY USING THE PHOTOALIDADE. (MANUAL OF PHOTOGRAMMETRY, 1944)
Context Canada
PART OF A COLLECTION OF HISTORIC MATERIALS FROM SURVEYS & MAPPING BRANCH, ENERGY, MINES & RESOURCES CANADA [NOW NATURALRESOURCES CANADA]. THIS PHOTOALIDADE MADE IN CANADA BY WELL KNOWN & LONG ESTABLISHED FIRM: CIRCLE & ARCS DIVIDED ON 921776 POCKLINGTON DIVIDING ENGINE.
Description
CAST IRON; COPPER ALLOY; PLATINUM; GLASS; ALUMINUM; STAINLESS STEEL; FERROUS METAL. CW PHOTOGRAPH-PAPER & PHOTOGRAPHIC CHEMICAL COMPOSITION.
Number of Parts
1
Artifact Finish
MOST SURFACES HAVE BLACK CRACKLE FINISH. CIRCLE & ARCS HAVE SMOOTH, BRIGHT SILVER METAL (PLATINUM) FINISH. GLASS PLATE SUPPORT FOR PHOTOGRAPH HAS BRUSHED SILVER METAL FINISH. ADJUSTMENT KNOBS, FINE ADJUSTMENT FITTINGS, MOUNTINGS FOR TUBE LEVEL CASINGS, ETC. LACQUERED BRASS. CLEAR GLASS PHOTO SUPPORT & LEVEL VIALS.
Artifact Markings
'THE/ THOS. POCKLINGTON CO./ TORONTO, CANADA' INCISED ON CIRCLE CENTRE. SMALL BRASS PLATE STAMPED '1' SCREWED TO RIGHT SIDE OF BASE. DECAL APPLIED TO BASE READS: 'EMR/ INVENTORY CONTROL-/ R.C. C.R. 634 007043/ EQ. CODE D'EQUIPE 6675-21-AAA-0259/ DO NOT REMOVE NE PAS ENLEVER'. CIRCLE DIVIDED 0-360 BY30 SECONDS. VERTICAL ARC DIVIDED 60-0-60 AT 30-SECOND INTERVALS; VERNIER DIVIDED +30-0-30+, READING TO MINUTES
Artifact Missing
APPEARS COMPLETE. TUBE LEVEL ON PHOTO MOUNTING PLATE IS CONTEMPORARY, BUT NOT ORIGINAL TO THIS INSTRUMENT.
Group 1
Exploration and Survey
Category 1
Photogrammetry
Subcategory 1
Plotting equipment
Material
metal->iron;metal->copper;metal->platinum;metal->aluminum;metal->steel;paper;synthetic;glass
Length
69.0 cm
Width
39.5 cm