Weston Model 594 Photronic Cell
And mis labeled "for "C" and "D" 2-cell flashlights". Clearly a two cell flashlight using the highest voltage cells Alkaline can only produce 3.
Searching patent class 362/186
There are a number of ways of measuring light. Lumens Wiki are a measure of all the light that a source can produce. The measurement is made with the light source inside a reflecting sphere so that light in all directions is captured. A Candela Wiki - the new version of a candle power is a measure of the visible light falling on a surface. Note both Lumens and Candela are measures of visible light only, not IR or non visible radiation.
So these units are not applicable to IR sources. The Weston Model Photronic Cell was designed so that it measures light with a wavelength response curve that comes very close to the human eye. For example when the Mini Mag Light has the reflector removed and used as a base, i. So the key measure is what a light meter reads at some specified distance from the light source.
This reading will depend on the product of the brightness of the source lumens and the ability of the optics to direct all the light in a desired direction. The same light source may be used for area illumination or as a spot light with a very narrow beam. The surface brightness of the spot beam will be much higher than when the same light source is used for area illumination.
This is very similar to radio antennas where the gain of the antenna comes by directing the signal in a narrow beam. Some light sources, like High Intensity Discharge Wiki: AEX25 lamps are easier to design optics for than LEDs and so can have higher surface brightness than another flashlight with a higher lumen rating, but not as efficient optics.
There have been a number of lanterns for use in battle areas. The more modern ones use the or similar spring top 6 Volt lantern batteries. The two most common types are the all battery version that's an almost cube plastic box holding a couple of lantern batteries and a sealed beam 6V lamp both of these are typically yellow , or the same lantern with a relay that turns on the lantern when the mains power fails. This Rolfan lantern is based on the common dual battery 6 Volt sealed beam design except: The problem is that you should NOT use a float charger on a primary battery.
This lantern was designed to work with a rechargeable an lead acid 6 Volt battery. Now to find a charging AC line cord. Deciwatt - generator powered by weight with variable gear ratio, DC output terminals for external light, phone charging or Steripen UV water purifier. These are collimators with a reticle that gets projected. These were used in the same way as laser pointers Wiki today. But unlike the red laser pointer that's impossible to see in a video of a lecture, the flashlight pointers can be seen.
Eveready Boy Scout Angle Head. D - single No. A portable source of light probably started with a cave man carrying a burning stick of wood. There have been many portable light sources based on burning something. Once the dry cell battery became available flashlights became more popular than they were when a lead acid or other wet battery was needed.
This web page is being done by adding a section after reading something on the internet, either an eBay item or reference material. Once an inventor name shows up then his inventions are grouped or the company the invention is assigned to has a group of related products.
I have included on this page what most people would consider a flashlight, but also any light that uses the No. And some closley related patents like anti reflection coatings or earlier lights. Not on the page are patents related to Flashlights as used on cameras. The key components of a portable light source are: Source of power, A way to start and stop the light source, A way to convert the power into light ,A way to control the light.
For a flashlight these would be: Lamps The early Flash Lights used an Edison type minature screw base lamp very much like the A problem with this lamp is that the filament location is not controlled. Part of the reason for that is there is no reference surface on the base to support good filament location.
The single contact miniature flange base used the flange surface as the reference plane for locating the filament and so allows flashlight reflectors to be designed that have the filament at focus without any adjustments. The miniature screw base Lamp has a built in lens and so does not need to be in a flanged base. There seems to be a disconnect between the battery makers and the lamp makers. The Leclanche type dry cells used have a nominal voltage when fresh of 1. The end of life voltage is taken as 0.
The lamp voltages seem to be about half way. The patent see below by Charles Burgess mentions this and his lantern has a two position switch so that a resistor can be inserted for the first few hours of operation and then the direct connection made for the remainder of the battery life. It's my feeling he was correct, running the Pocket Flash Lights on a full 3.
The Victor X solid lamp is in the stand for the photo. When it's on and you are looking at a side view like this there is not much light coming out, almost all the light is aimed in the narrow beam like for the The expensive part was getting good wood bits. The brass hardware is from the No. Filaments Eveready Mazda 1. Q quick check of three os the flattened bulb type lamps showed they all had this type of "S" filament. I'm fairly certain that all the other lamps have coiled Tungsten filaments.
Based on measuring one I think the thread is 14 TPI with a pitch diameter of 0. Those numbers are "nicer" than the metric equivalent 1. Let me know what it really is. The Ever Ready Osram lamps had this patent date marked on the base. The Edison base was a cylinder that was all threads this invention makes the base more cup shaped and pours molten glass into the base that attaches to both the center contact and the base.
It's mentioned on the Antique Christmas Light site about Eveready page 2. LAIB, Dec - color filter as 2 pard shroud covers bulb Lens, Kovac, Jun - a very complex shape of reflector behind lamp Electric Lamp, Claus, May - incorporate reflectors, lens, multi filaments, etc. Integrating Sphere also see: It may be that these very early batteries had a lot of internal resistance, so although they measured 3 volts open circuit, when connected to the lamp the actual voltage across the lamp was less than 3.
I feel that connecting two modern 3 volt Alkaline cells to the lamp would burn it out. The tabs are made out of a dead soft metal and do NOT have spring action and so do not make good contact with the lamp base. Because of the poor spring action this battery requires some "fiddiling" to get it to work. Or that may be just the nature of this type of battery? Hawthorne made carriage, bicycle lights and lanterns.
A quick connect pipe clamp mount for a spot light allowed carriage mounting or to about anything round. Conrad's first flash lights were made using fiber tubes which are insulators. That makes it easy to bring out two terminals which when connected turn on the light. The big problem with that is when the switch is in the off position and any metal touches the two terminals like in a tool box the light is turned on and the batteries go dead.
The user later takes the light out of his tool box and the switch is clearly off, but the batteries are dead. Seem like those batteries don't last very long. It's relatively easy to make a push button switch that normally off and momentarily on, the nomenclature is: A further refinment is to place the switch somewhere so that it's very easy to use allowing full operation of the flashlight with one hand.
Care and Feeding Often the flash light I get on eBay is very old and had rust and corrosion on some of the metal surfaces. I don't think it's good to just leave that alone since it will continue to corrode the metal.
I have my first flashlight book on order but these lights need help so I'll present my method now. If you know of a proven method please let me know. Utility patents use numerical class and sub class numbers to specify the filed of the invention. New things get invented and so new class and sub class numbers are assigned.
When new classes are assigned the classification of an older patent may change to be in line with the new numbers. The early patents do not have any class numbers on the printed copy. Both the Utility and Design class numbering systems are indented. First by bold titles then by dots preceeding the numbers. The other top class numbers are in some filed related, such as electrical contacts, mechanical fastners, etc. For Ilumination lamps, or those combining both illumination and signaling functions, see Class D For lantern or flashlight, see D Electric Light Bulb including photo flash bulbs.
Hand-held, body-attached or lantern type Includes base. For lantern bracket, see subclass For bulb cage, see subclass For static signaling lamp, see D MacKaye, Oct 6 , - uses three No. Scanlon, Mar 28 , - Electric Torch, J. A cap and be put on the nipple so a bang will coincide with the flash of light. This patent has a problem in that both switch terminals are on the outside of the flash light.
When the switch is off if any metal makes contact with both terminals the light will be turned on. This happened a lot when the flash light was stored in a tool box where things like screwdrivers, pliers, etc. Altough the patent talks about a parabolic reflector I think they were painted white and considering the diameter of the 14 screw base bulb not much light came from the reflector.
Most came through the Bulls-eye lens. The patent also covers a gas lighter that uses the same cylindrical the patent calls it tubular battery and switch housing, but replaces the reflector assembly with a long stalk and an external hot wire to light gas. The lamp, although made like others of the time, was a minature version specially made by Eveready and the patent talkes a little about it's construction. The floppy disks were branded Verbatim.
Later they changed the company name to Verbatim. Might be the Watchman's lantern? The data sheet says: The three "D" cells fit nicely but "F" cells are much too large. It fits the Watchman's very well. Max battery size 4 x 3. Most likley a three cell. There are a four fiber board sheets that are now warped. To make the light functional they need to be rejuvinated. The 3R12 might be too small and the 3E25 too large. E10 based lamp is open and has no voltage markings. March company formed. Stuckelberger, Nov 20, , Electric Candle, M.
Then interior lights for cars and clock cases. Old batteries have drained into the cup of the base where the battery spring and a post are located. The post is threaded and unscrewing it gives access to the switch compartment. The cup has been sitting a Kroil for a number of days, hopefully I can get into the switch compartment and clean it up.
The three dots in the black band are Radium activated glow in the dark markers. On this light so far I haven't seen them glow. They do emit about 10, Counts per Minute into a pancake Geiger tube. These are not dangerous if left alone. It would be bad to sand the dots and make radioactive dust. On the bottom is a metal plate that's attached by what looks like tubular rivets, but they are really part of the candle pot metal base that's been treated like a rivet.
To remove the metal plate just grind off the top part of the rivets. On the back of the switch lever and a part of it is a stair step contact. Below is a lever hinged on one end from an insulating block, a spring connects the lever to the center contact that goes up to the battery spring. The other end of the lever is pressed up against the black button.
My switch was not working. The problem was that either the star washer that you can see on the bottom center which is supposed to take all the slack out of the switch lever to metal plate joint lost it's spring or the lever got bent a little. By reforming the lever with pliers it now works like new. To reattach the metal plate the holes were drilled and tapped and pan head screws were used. The black button is the switch used for automatic operation.
The rotary switch is labeled "Auto" and the positions are Out shown off, "Constant" auto function works and "On" where the light is on all the time. It seems the labels don't match the function too well. When sitting on a table it's pleasing to look at. If you grab the milk glass globe and lift it very gently the light does not turn on, but if lifted normally it turns on.
When sitting on the table a soft light comes from the milk glass globe, similar to a candle light, but much nicer since it's diffused and is a warm color. On the bottom there are 4 rivet heads that it sits on so there's a small gap that lets out a little light from the reflector. When lifted up there is a reflector and it can be operated like a normal flashlight. The lamp is mounted "backwards" in the reflector, i.
This allows light to reach the globe and the reflector. But it makes it harder to adjust the focus of the lamp in the reflector which requires opening the case, turning the brass knob, closing the case testing the beam shape, and repeating a number of times. The base is marked: Eveready Masterlilte Made in U. I wonder if it's also used on walking canes? Weighs 1 pound 3 ounces a substantial heft.
The four vertical ribs are formed leaving a slight gap behind each. If a flat blade screwdriver is placed in two of these gaps after rotating the base counterclockwise, there is a recess in the base to make it easy to remove. The slots to use are the ones NOT adjacent to the two outer rivets that hold the reflector. Brass sheet metal is used for the wiring and is trapped by wrapping an insulator around it then wrapping other sheet metal. The same method as used for the Art Deco Pocket light.
A box 4" x 4" x 4" will hold the table masterlite. Bill Utley's page has a photo of Evenlyn Kelley on the set of "Anything Goes" with the table masterlite on a bedside stand along with a Western Electric telephone. Graubner Union Carbide , filing: Can be used on lathe or other machine tool to check runout using probe. D Flashlight, Herman G. D Flashlight, Jules P. D Handle for an Iron, Charles S. Garland Ray-O-vac , Mar 13 D Pocket Flashlight or the like, P. Kelley Cresale Inc , References: Patche, Genesy Electric Lantern Co.
Packer, March 10, - explosive atmos Flashlight, O. Wood Blake Mfg , May 8, D Flashlight, Anthony J. These are very similar applications and it's common for a patent to mention both. The tab above the lamp hooks over the lip of the wood cane so the lamp is down from the top but not seated in the bottom of the hole. The metal cap fits nicely. A theory of operation is that a missing spring pushes the battery and sheetmetal part up slightly which pushes up the metal cap. When the metal cap is pressed down the sheet metal part comes in contact with either the spring or a metal part holding the spring completing the circuit.
The red O-ring in the cap would hold a glass lens. An electric current passes through the person holding the cane, at the time thought to be medically beneficial see my Faradic web page. Prior to being one of the founders of Delta Electric John J. Brownrigg worked in the telephone business. One of the first products of Delta Electric was a Coin Collector. Case Delta Electric Co , [filed: D Portable Electric Lamp , J.
Another theory is that the person who made the artwork transposed numbers Dyslexic. For example D is dated Sep 22 which is off by one digit in the year. This is very similar to issued Aug 31 , see below. D Flashlight, Walter B. Moxley - Light Weight Lantern Co. Streamline 2 D cell flashlight. This is the same design as the original Moxley except it's for "D" cells instead of "F" cells.
As an "Official" he was not part of the union, received a salary and travel expenses, and was required to wear a suit and tie. Even so, he did oversee many night time travesties, like train wrecks, etc. His wife was continually ironing and washing when he would come home full of mud and grease. Usually his excuse was he couldn't see in the dark and had slipped or fallen in the mud.
Becuase of their reliability were adopted for railroad signaling. Very important that train engineer see the signal at night. It takes a couple of batteries the same diameter as the common "D" cell but longer called "F" cells. For more on "F" cells see my No. The center off switch selects one of the two bulbs. Since the bulbs appear to be the same this must be a spare bulb system that can be brought into play very quickley.
Made from sheet brass. Iron or steel wires used for the stand at the bottom. Hand stamped in the side NH One lamp might say T11N and the other 2. Uses a single battery, most likley a 6 volt "Lantern Battery". II flashlights used "D" cells. D Carbide Lamp - why? D Design for Acetylene-lamp Body - why? Two wide, two high battery box very similar to the Justrite Light Stick. Slide switch on top of battery box. Belt clip on back of battery box. Screw on head unit both can remove reflector to change E10 based lamp and focus it.
If you know more about this headlamp or Metal Ware Corp, let me know. On the back is a belt clip and on the bottom is a bail allowing it to be supported in many ways. These were used by the phone company among others. Focus by turning the lens ring. Spare lamp inside head. Brown - Miner's electric lantern, batteries behind head lamp in front.
Packer, Justrite Mfg Co. Pixley, Armspear Mfg Co. Carbon is a key ingredient of both gunpowder and dry cell batteries. Both dry cells and metallic cartridge ammunition are metal cans that hold the carbon based chemicals. So a company that makes black powder ammunition would already have some of the technology in place. So it's logical for Winchester Repeating Arms Co. A flashlight with the cap marked: But the assignee is the Winchester Repeating Arms Co.
The top slips off to change lamp. Battery door is hinged, but has some depth, not just a flat plate. Probably 3B cell battery. There's a nice silvered reflector above the socket, but the spherical lamp marked "MAZDA" has a horse collar made of white plastic that covers up the reflector.
What's up with that let me know or if you know anything about this pocket flash light? Hook to hand at foot of bed, switch attached to side of bead, battery under bed. The metal case is one electrical terminal and there's a slip ring in the top and a contact in the battery holder part, so you can rotate the top mirror to any angle desired. If the top part is pulled out or pushed in past the slip ring the light will turn off.
I did it by pushing in but a few minutes later when it was picked up the battery compartment was very hot and the cells dead. Pushing in caused a short between the ring contact and the case even though the contact is wrapped in fiber insulation material.
Best to remove the batteries when not in use. The top mirror was loose but a few drops of super glue fixed that. The lamp is on in the photo. I've erased the call outs this and the miner's lamp below are both "head lights" so maybe that's why the portraits? Since the window shade roller is wood electrical contacts and be made to each end which are insulated from eachother.
D Flash Light, Gustaf I. Combined Flashlight and single tube regenerative recciver. Power Fail lighting wherre relay turns on battery when main power fails, Railroad application, but general patent. In the top half in the optical path you can see a vane sticking up. It sets the right frame edge. Since the perf is at the bottom of the lower half. If the height of this vane was reduced 2.
East to test, just lift it up a couple of mm. With the top open you do see the full super 16 frame. Need to wait till dark to check the largest size image. Click on image to get pdf version where layers can be turned on or off. D Flashlight, Leopold C. Holds 1 "D" cell.
Dircksen, May 22 , Electric Lamp, A. James, Apr 7 Flashlight, O. Wood Blake Mfg Reflector, Myron. Simpson, Jun 16 , - Ophthalmoscope? Martens, May 5 - with light Flashlight Attachment, G.
Hyatt, Sep 7 , - angled magnifying Glass. Collins Flashlight, William I. Barricade Flasher uses 6 volt battery gravity switch turns off when on it's side, laminated transformer used as part of strobe light power supply References: Lamp at each end. When carried with are down light horizontal the angled heads make a pool of light for the usher and another pool of light for the patron.
Roskaxn, Mar 25, , - minimalist sheet metal with feet to plug into pumpkin. Brown Electric Cap Light, A. Gey Flashlight, Willis B. Beard Flash Light, Leslie C.
Weidman Flashlight Construction, John J. D Portable Light, John H. Gey, Oct 16, Trimble Signaling Device - Attached to back of drivers hand powered from car uses Mercury switch - not here Flash-light Traffic Signal, J.
Trumbull Fan or Blower, W. Popovich, May 6 Pieper, Jul 30 Flashlight Fan , J. Four "D" cells side by side in short cylinder References: Noffs, Dec 27, - appears to be very reliable design - sounds like it used "D" cells, not hard to get cells. A drum moves in a start stop manner to display a small number of frames by reflected light.
Gits, Apr 10 Popular Mechanics, Sep , page Photo is a paper doll made by cutting out the patent drawing. There are two pieces that get stapled together.
When ready to use a two cell lamp would be screwed into the large sheet with it's base contacting an eyelet at 62 and the box folded up. The string and button type of office closure is on the outside to hold it together. Not sure what size battery it was intended for, could be dimensioned for almost any pair of cylindrical cells.
One of a number of minimalist flashlight patents. Burhans Battery Hand Lamp, C. Bledsoe Badger Carton Co , Sep 19 Lyhne, Jan 15 Handlamp Switch, H. G Chase Co Mercury switches make and break the curcuit as a car stops. Flashing Warning Lantern using bi metal strip References: Grimsley, Aug 20 Flashlight, Donald G. Three transistor circuit, inductor in series with lamp to allow a high power lamp to be switched. In TEST the switch housing when connected to the case turns on lamp. Meginniss, Feb 27, Flashlight, Paul O.
Golder, Sep 16 , - machined Means for actuating electrical switches, Theophile A. The sealed beam lamp has been retro-fitted with a multiple LED lamp to lower maintenance costs References: Wendt, June 27 Multicell Battery, H.
Anthony Electric Storage Battery Co. Screw Products got their start with this patent. See the Flashlight Collectors newsletter 80 Winter Baird, Flashlight, A. Patent Number Title Issue date Door lock illuminating device Oct 2, Battery powered auxiliary lighting fixture with a timer Nov 18, Interior light for U. Joffo, Oct 31 Flashlight, George P. There is also provision to recharge them in place. Note earlier versions of the Petzl head lamps used the unit style 4.
When unscrewed the lamp is turned on and the beam can be adjusted. This Flash Light has no markings. It uses a glass lens that is NOT it's focal length from the bulb but instead much closer. In the photo above you can just make out the broad hot spot about two diameters in front of the lens. When the lens is moved a couple of inches forward the hot spot is just a few degrees wide, but it would take a longer tube to hold it there.
So by locating the lens where it is the beam is something like degress total. Maybe this is the wrong lens for this light? The Lens is convex on the outside and concave on the inside. The inside is also recessed. The reflector, bulb holder has a disk connected to the threaded part of the bulb but that is insulated from the metal reflector and case.
The center of the bulb makes contact with the positive battery terminal. The switch connects the case to the disk. The conducting disk as half of a switch where the other half is the sliding part and the use of an adjacent insulating disk so that the metalic reflector does not connect the lamp base to the flash lite case is used in the following National Carbon Co patents: If this was a depression era flash light then the use of a single rivet to attach the switch surly was a cost saving compared to other switch designs that use 3 , 4 or more rivets, with there associated holes and installation labor.
The body was black and there were gold stripes in groups of three running parallel to the long axis. The head was plated, maybe Nickel and the battery brass battery cap was black. The problem was corrosion at the joints. After dissambely and scrubbing all metal surfaces with Renaissance Metal De-Corroder and a through rinse under warm tap watter and a good drying including some canned air, it now is functional. Eaton prior to Niagara? Portable Self Contained Both are addressing the short prevention aspect of the patent.
The switch shown looks like an inch worm and is open under the bump. It's illustrated in issue 78 summer of Flashlight Collectors. This next patent is prior art to a battery powered pocket flash light. Notice it was called a Pocket Lamp. Pocket Flash Lights have a similarity to bicycle lights, but are much smaller and the lamp is usually pointing up rather than forward.
They were made in different sizes, where the design is the same for all of them. The tab type unit cell 1. The narrow Pocket Flash Light uses an eyelet instead of the rivet at 11 , the contact in made by bending the spring 10 rather than the stud 7 and the slide switch 13 has open ends which cost much less to make than the closed end version used on the patent style light.
Both of the Eveready Pocket Flash Lights uses a 2 cell battery with the factory lamp rated for 2. Dec 30, , Issued: Jan 25, , Issued: Insulating case, series connected cells for 4. Special bulb with reflective coating and no top protrusion. Pocket Flashlight on the right is: Both marked Eveready pat. Engraved has lamp with white plaster of paris engraved 2. There is a lens above the body and top mounted switch beside lens.
Maybe a wood block shaped to fit the cells and lamp, then packaged in a watch case or other outline. These are a sub class of Pocket Flash Lights Ad. Each pull of the trigger makes a very brief flash of light which if it hits a photocell counts as a hit.
Used in carnival shooting galleries. The ratchet wheel may also count shots? Shooter transmits an omnicirectional radio pulse coded signal and all targets that would be hurt by that type weapon respond with an IR pulsed signal. The shooter has a 3 lens optical IR sensor boresighted with the barrel so only a traget that was aimed at would count as a hit. Also uses the cigarette lighter case type of latch where the edge of the sheet metal spring is the button.
The round object just to the right of the latch is a rivit holding the latch-spring in place. The reflector is a seperate part that has been soldered to the top case. AA cells are way too small, probably uses what's called a 3 "B" cell battery pack. Lamp is glowing dimly at 1. Pocket Flash Light behind "break glass to get light" box might be mounted in elevator. The Snap-Lite was a very low cost light based on two AA cells side by side with a lamp connected to a lid. When the lid is opened it both rotates the lamp and turns it on.
These were imprinted with a business name and "Compliments of. The cells can not be replaced so it's a throwaway, but some people kept them even though they no longer worked. This was the first use of the Burgess patent which involved forming the Zinc can as one piece of metal instead of the prior method of soldering a cylinder then soldering a cap to the cylinder. Apparently the internal chemicals are exhausted before the zinc has a hold eaten through it, hence a number of these still survive.
Photo i s of a No. In the oval on top is: On the clip that holds the screw based lamp: Stamped into the floor of the top compartment: D Battery Hand Lamp, J.
Snap look alike, but lamp is fixed, lid opens and activates switch. This art deco light is marked: The case and the working part can be seperated so that the working part can be used elsewhere. Osean Flash Light, A. Mitchell Flashlight, B. Maranda Electric Pocket Lamp, C. Boltshauser Battery Lamp, George J. Akerley Disposable Flashlight, Horace B. Paulson - identical halves Minature Light Source, H. Glwesky Realist Inc , Apr , - fits into top of dummy key, button cell. Hook on end of chain allows holding chain in out position keeping light on.
This unit is mounted using the three holes in the back plate. The front cover has two tabs that fit the slots. The slots have spring wire at each end that grabs the cover tabs. The Wallite can be mounted not only on a wall but also a ceiling.
The printing says "Brass cap of battery should point in direction indicated" Clock work for one minute timer Back showing the three mounting holes. Victor Pocket Flashlight The prefocused lens casts a narrow beam with only a small about of general light See lamp photos above for Victor-X 2. Most likly takes a three "A" cell battery like the MN The switch is unique.
Under the button is a narrow post and below that a disk. The leaf spring pushes the disk up into the round hole locking the light off. The top lens is oblong as is the reflector. Maybe made for or in Austriala. Many years making Kerosene lanterns.
Some photos at Electric Lantern. Pratt, Jul 4, , - when in a tool box pressure on the light will not turn it on Insulated Flash Light, F. Darling, Mar 31 , - rectangular style "d" hole bracket for hanging on nail or screw D Electric Hand Lantern , George Barber Very similar to the Niagara hand lanterns. Stimson, May 18 , - spot or diffused hand lantern, cylindrical cells arranged like revolver Portable Electric Lamp, Roy L. II , Orville T. Adams and Westlake Co - Adlake Co.
Baird, Feb 24 , - 6 "F"? Genesy, Genesy Electric Lantern Co. Hall, Federal Electric, single lamp, 6v batt, railroad stype, thick glass dome over lamp. Pearson, Feb 6 , - railroad type Electric Lantern, H.
Moxley Electric Lantern, Frank T. This company made parts related to carbon arc lights then they made a combined steam turbine and electrical generator specifically to power an electric headlight for steam locomotives.
Later they got into making warning lights for locomotives, the idea being to oscillate or wobble the headlight so that the light is more attention getting. Warning lights for firetrucks have a similar function and work in a similar way. Packer, March 10, , - dual lamp, 6 v lantern battery, railroad style - no exposed switches allowing for a hermetic sealed lantern.
Safe for hazardous locations. Edison Inc , Apr 8 Lamps Flashlight lamps first of all must have an operating voltage that's compatible with the voltage supplied by the flashlight. But after that the current or power of the lamp is related to the capacity of the battery. But the table inside both models is for light for various tasks like reading, etc.
The geiger counter reading is only 4, counts per minute for this meter, much less than for the above. Probably because the white diffuser blocks the radiation. With the Bakelite lid closed only background radiation is measured. One of the earliest photoelectric exposure meters and marked the introduction of the Weston film speed system Wiki.
It wasn't till that the Weston exposure meters switched to the then new ASA system. I expect at that time it amounted to no difference and may have been done so that Weston could not claim to be the total basis for the ASA system. In the late s film speeds Wiki were not yet standardized between manufacturers, so each brand had their own system. About based on patents on meter face. This is very similar to a light meter I used decades ago.
I remember the hinged light baffle that also changed the meter scale. Note in the photo where the baffle is opened the meter is reading the daylight in the room. Physically looks like the still camera exposure meter, but the circular calculator and meter face are specific to movie cameras.
Instruction book Weston Film Speed booklet: Lumens Wiki are a measure of the total visible light emitted by a source and it typically measured using an integrating sphere Wiki. For example the Lumen output of a LED would be the same after it's lens was filed off as it was with a narrow beam.
But the Foot-Candle reading with a narrow beam will be much higher than for the same LED after filing off the lens. On the other hand some flashlights advertize high lumen numbers, meaning they contain a bright LED, but do not have the optics to focus all that light into a beam to provide a high Candela value on the subject being illuminated.
In the s there was a lot of patent activity related to adding sound to moving pictures typically done using vacuum tube technology. There was also a lot of work on transmitting images electrically, later called television, again typically using vacuum tube technology.
In both these applications speed of response was very important. But for measuring light for photography or to determine the light needed for various industrial applications a light meter with a response matching the human eye was required. Design probably from the late s, using "GE" film speeds. They switched to ASA film ratings in Wiki.
Sold by the Army Exchange Service. An Integrating sphere Wiki was used by Edison when testing his light bulbs. It collects all the light from a source and so removes any directional aspect so gives you a measure of the total light output.
I've watched eBay for a used one that's small, but they are still thousands of dollars. Electromagnetic Radiation is part of the electromagnetic spectrum and broadly speaking covers the wavelength range of 40 nm to 1,, nm. This is from short Ultraviolet through long infrared IR. Only the narrow band of about to nm blue to red is what's called visible light Wiki. Near IR Wiki light about through nm can be seen by using a digital camera that has the IR blocking filter removed.
This is sometimes called X-Ray since you can see through some clothes. When measuring the light output from something that makes light there are two ways. One is to measure the total power output at all light wavelengths and the other is to measure only the visible light output. If the light is to be used by people seeing something with their eyes then the visible light output is the important thing.
Note that digital cameras have silicon imaging chips that can see near IR light, but they also have a filter that eliminates near IR light so that the overall response of the imaging chip comes close to human eye response so that color photos will look correct.
There are a number of ways that light can be converted into an electrical signal allowing it's brightness to be measured. One of the key problems they face is to have a response that matches that of the human eye Wiki: Luminosity , CIE color space. If the spectral response of the sensor does not match that of the eye then the reading may be too high or too low.
When modern Silicon sensors are used to measure light something needs to be done to cut the IR response of the Silicon that's much more sensitive than the eye. Weston Photronic Cell I think the Weston Photonic Cell is the basis of a number of specifications for visible light and they are still being made today by Huygen the company is named after Christiana Huygens [ Wiki ]. Transactions of the I.