Saw this Photelometer on eBay with the title "Antique 1936 Cenco-Sheard-Sanford Photometer Photelometer Central Scientific Co" (Wiki). I got it because this optical device contains a Weston Light Meter in two parts and because it's a precursor to the Spectrophotometer which is a form of optical spectrum analyzer.
Trade Mark Reg. U.S. Pat. Off.
U.S. Patents Nos.
2,051,317 - 2,051,320
Cat. No, 41000 Ser. No. 203
6 Volts A.C. or D.C. 7 Amp.
Reg U.S. Pat. Off.]
Lights On/Off Meter Read/Off
Central Scientific Co.
New York - Boston - Chicago - Toronto - Los Angles
Made in U.S.A.
Pretty much all of this unit is metal, mostly cast iron and some sheet metal.
There are no optics, just a custom lamp. Almost a point source.
The input is a Carl Zeiss Lens assembly. Starting with an diaphragm adjustable from 1 mm to 33 mm diameter. Behind the diaphragm is a rectangular mask 6 mm wide x 15 mm high then a 40mm focal length lens. There is a green filter in front of the Weston Photocell. Between the back of the mask and the photocell is a 20mm gap where the sample holder can slide back and forth to select one of the three samples. I expect one of the samples holds clear water and maybe another one holds a calibration fluid leaving one position for the sample to be tested.
There are three detents on the slide, but I don't see anything to engage them.
The sample might be held in a test tube 5.8" dia x less than 1-3/4" high.
2-1/2" wide x 2-1/4" hi slide with green filter. See Fig 8
Wratten filter (Wiki) # 74 - dark green monochromat, Transmits 10 percent of green radiation and virtually no yellow radiation from mercury-vapor illumination.
Consists of two parts.
Weston Photonic Cell - Note the Weston 594 Photronic Cell has a response curve that matches human vision and is used as a standard. This cell may be of similar construction in order
Weston Model 440 Galvanometer. Serial No. 8947. Resistance 157.2 Ohms, External resistance for critical damping 740 Ohms.
This is a custom meter made for CENCO with a scale marked 1 to 100 with no units of measurement.
Another Model 440 on eBay that shows 152 Ohms is marked 0 to 15 uA with 0.6 uA per division, ie a total of 75 divisions.
Fig 1 Chassis, lid closedz
Fig 2 Chassis, lid open
Note lamp at left is to illuminate meter face
MAZDA 63, 3 Candle Power, 6 - 8 V
Fig 3 Lamp House
Fig 4 Sample Holder seen from Lamp House side.
Note test tube mask behind Lens.
Fig 5 Green filter in front of photocell and behind sample.
Fig 6 Three removable sample holders ride on a slide.
Fig 7 Empty sample slide
Lid stop holds lid when open.
Full scale adjustment for part of calibration.
Fig 8 2-1/2" wide x 2-1/4" hi slide with green filter mounted.
Note two thumb screws on long spring loaded posts.
3-3/4" di.a magnifying glass in lid.
Fig 9 If photocell is pulled out and the meter switch set to Read, the meter pegs full scale, that's to say it's a very sensitive light meter.
353098 Hemoglobinometer, E.P. Von Marxow, Nov. 23, 1896 - ruby glass wedge
548717 Centrifugal machine, P.P. Metzger, Oct 29, 1895, - under table clamp, two test tube hand cranked seperates red blood cells.
Samuel L Fox, Edmund S Clare,Queen & Company, 1900-09-22 - "Dare Hemoglobinometer" - uses candle and ruby glass wedge in the form of a disk
1414261 Hemoglobinometer and illuminating device therefor, Dare Arthur, 1920-02-24 - has built-in light source instead of using room light, uses ruby colored glass disk measuring method
Sheard Charles, Arthur H Sanford, Dana A Rogers,1933-03-11 - uses green filter and lightmeter
2051320 Apparatus for using photoelectric cells quantitatively,
Marshall N States, Central Scientific Co, 1934-07-02 - CENCO Photelometer, uses green filter and lightmeter
2783938 Centrifuge for capillary tubes, International Equipment Co, 1954-11-15 - ... to perform hematocrit determinations on blood samples to pack the red blood cells to the bottom of each small bore capillary tube so that accurate determinations of the red cell volume in whole blood can be obtained"
8203704 Multi-stream sensor for noninvasive measurement of blood constituents, Cercacor Labs Inc, 2009-08-03 - ...glucose, oxygen, met hemoglobin, total hemoglobin... LEDs - finger tip - optical sensors
While researching the patents on the Photelometer discovered a more modern version made by American Optical and found one on eBay (long obsolete, so low price).
This unit works in a manner similar to the Photelometer above in that it makes use of differences in the spectrographic transmission caused by hemoglobin. The light goes through a green filter prior to coming to the blood sample and again through another filter that's part of the eyepiece. There are two paths for the light one goes through the blood sample and the other goes through a wedge that attenuates the intensity of the light. The wedge is adjusted until the light in the adjacent windows looks the same. This is a lower cost design than using a light meter as in the above Photelometer.
Label (Fig 4):
American Optical Company
Buffalo, New York, Made in U.S.A.
U.S. Patents 2,396,260 - 2,482,650
Des. 124132, Can. 458,321
Lamp Mazda #233 (Purple Bead)
2.3 Volts 0.27 Amp. G 3 1.2 Bulb
Battery: Size "C" Flashlight
Disconnect from Line Source
When Instrument is Opened.
C.S.A. App. No. 2927
Ser. No. 41592
Fig 2 Small box contains preparation supplies
and a blood sample Chamber
Fig 3 Cylindrical container has round toothpick like for
breaking up red blood cells.
Blood sample Chamber sitting next to sample slot.
Socket at left is for external power.
Button at bottom to turn on light (note no slot for adjusting lamp).
Fig 4 Analysis half at top, light source at bottom.
Fig 5 The eyepiece has a green filter. A blue glass wedge is
slides to vary the intensity of light.
Albin A Gradisar, Morden G Brown,American Optical Corp, 1942-04-25 - hand held unit, battery powered, uses sliding wedge
D124132 Design for a hemoglobinometer, Albin A. Gradisar, Et al, Spencer Lens Co., Oct 20, 1942
2482650 Optical comparison hemoglobinometer having a reflector supporting transverse partition,
Morden G Brown, Harry F Lundberg, American Optical Corp,1945-12-26 -
2486956 Optical comparison hemoglobinometer with switch for use of selfcontained or external Power sources, Harry F Lundberg, American Optical Corp, 1945-11-24 - when external power plug is inserted it opens battery circuit
3533698 Optical comparison hemoglobinometer with a rotatable light source,
Morden G Brown, Norman W Shatzel, 1967-09-11 - improvement to the 260 patent where lamp filament can be centered. (not part of this unit)
Optics - Optical Patents - Optical Bench -
Optical Spectrum Analyzers
Weston Light Meters
The Photelometer and its use in the Clinical Laboratory, A.H. Sanford, C. Sheard and A.E. Osterberg, American Journal of CLinical Pathology, Vol 3, No. 6
Adapter for Sheard-Sanford Photelometer, A.S. Giordano - a glass block (8 x 5.2 x 3.4mm) with a 1.05 cm hole reduces the volume of blood from 20 cc to 8 cc. This means that instead of puncturing a vein, an ear or finger can be used.
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