General Information

Serial #

N/A

Part Number

1

Total Parts

1

AKA

N/A

Patents

N/A

General Description

CAST IRON; COPPER ALLOY; PLATINUM; GLASS; ALUMINUM; STAINLESS STEEL; FERROUS METAL. CW PHOTOGRAPH-PAPER & PHOTOGRAPHIC CHEMICAL COMPOSITION.

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

69.0 cm

Width

39.5 cm

Height

45.0 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Exploration and Survey

Category

Photogrammetry

Sub-Category

N/A

Manufacturer

AKA

POCKLINGTON

Country

Canada

State/Province

Ontario

City

Toronto

Context

Country

Canada

State/Province

Unknown

Period

THIS TYPE OF INSTRUMENT PROBABLY USED 1940S-1950S, AND POSSILY LATER

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.

Function

TO MEASURE HORIZONTAL & VERTICAL ANGLES FROM AN OBLIQUE PHOTOGRAPH. USED FOR HORIZONTAL & VERTICAL POINT SELECTION FROM HORIZONTAL PHOTOGRAPHS.

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)

Area Notes

Unknown

Details

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

Missing

APPEARS COMPLETE. TUBE LEVEL ON PHOTO MOUNTING PLATE IS CONTEMPORARY, BUT NOT ORIGINAL TO THIS INSTRUMENT.

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.

Decoration

N/A