Author Topic: Pear shaped or straight sided bulb? (Read 13531 times)

Tim · « **on:** July 18, 2001, 08:27:00 pm »

Here's one that is an oddball (to me anyway!) I found this in the local antique mall last weekend:

I think this is the first straight sided bulb I've come across of this shape - notice the tubular shape at the base. So is it a pear shaped bulb (PS) or straight sided (S)? At $20, I couldn't pass this one up!

The bulb measures 7 1/2" long.

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-Tim
BulbCollector.com
DewCollector.com

Chris W. Millinship · « **Reply #1 on:** July 19, 2001, 06:59:00 am »

Fantastic looking bulb Tim! A bargain for sure.

That unique shape...well according to the handy bulb shapes guide just over there.....hmm. Not certain. My best guess is it is neither of those- it`s too curvy for an S or a PS. "A" perhaps? It`s kind of hard as different sizes of different shapes can look quite different to the untrained eye. My eye still needs more training it seems

I expect mr Hooker will know the proper answer though- James?

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Tim · « **Reply #2 on:** July 19, 2001, 12:32:00 pm »

Hey Chris,

I'm not sure that is an "A" shape either but I'm no expert - you may be right. I'm thinking the shape might predate the "PS" shape, but I haven't been able to find a smiliar shaped bulb in any of my material that might help me date it.

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-Tim
BulbCollector.com
DewCollector.com

Bob Masters · « **Reply #3 on:** July 19, 2001, 12:44:00 pm »

Hey Tim,

I just spotted the EXACT duplicate bulb shape in my Elliot Lewis catalog (circ 1915-1920) and they call it a Mazda "B" lamp for use in mines.
It shows it to be an S-30......8" approx length, 275 volts, 100 watts at $1.25 each,
with a medium screw base.
Only thing is that these are Buckeye Mazdas.

-Bob-

Tim · « **Reply #4 on:** July 19, 2001, 12:50:00 pm »

Hey Bob thanks. Is this the same catalog that you copied for me a few years back? If so I will look those copies up when I get home. Otherwise, can you scan the page for me or post it here?

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-Tim
BulbCollector.com
DewCollector.com

Chris W. Millinship · « **Reply #5 on:** July 19, 2001, 01:34:00 pm »

I think Bob sent me a copy of that catalogue too- hold on, let`s see if I can find it, I saw it just the other day.

Thinking of it, yes it`s probably not an A. Might just be a stylised S- for the larger-than-normal bulb size.

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Bob Masters · « **Reply #6 on:** July 19, 2001, 02:40:00 pm »

Tim & Chris,

Yep, it's the very same catalog. The match is stunning. Same stem length and everything.

Tim,
I'm sure that I copied all of the bulb pages for you. But since they were FAX'ed I don't know If the posting will look so good.
I can scan the pages of that catalog at on my brothers scanner if you want me to.

Chris,
I'm not sure whether or-not you got all of the pages.

-Bob-

Chris W. Millinship · « **Reply #7 on:** July 19, 2001, 02:48:00 pm »

No worries Bob I think I found it....

Looks about right to me

. Tim, does it look like a 275 volt lamp to you?

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Tim · « **Reply #8 on:** July 19, 2001, 03:36:00 pm »

Thanks guys! I think you have identified it for me. Any hard date on that catalog?

Chris, the voltage on the bulb isn't marked and I haven't tried lighting it yet. If I get a dim glow on 110/120 volts then I guess this will verify it's a mining bulb.

Now the next question: Why 275 volt circuits in mines (or mining work)? Strange voltage eh? Could such a bulb have been used to light the inside of a deep mine shaft? The price for the bulb states $1.25 and I wonder how much that translates to now?!

Thanks again bulb gurus

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-Tim
BulbCollector.com
DewCollector.com

Chris W. Millinship · « **Reply #9 on:** July 19, 2001, 05:42:00 pm »

My best guess to the odd high voltage is that perhaps mining machinery- pumps, hoists, ventilation plants- used a higher voltage than "regular" mains, for better efficiency- less volt drops along the inevitable long cable runs, etc. And for simplicity`s sake, they would perhaps just want to run the lighting off the same high voltage generator? Hence the 275 volt lamps.

Price wise, well I don`t have the entire light bulb section of that Elliot Lewis catalogue but a "special lighting service" 220-250 volt 50 watt B lamp (in S-19 glass) was just 37 cents. Regular 120 volt hosehold lamps would have certainly been less, perhaps by half, so $1.50 must have been a moderately priced lamp. FYI the biggest 1000 watt Mazda C lamps (of a similar voltage range) were $5.25- definately a lot of cash in those days!

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Bob Masters · « **Reply #10 on:** July 19, 2001, 07:08:00 pm »

Hey Guys !
The catalog is Elliot Lewis No. 10 and belive it or not, the only date I've been able to find anywhere so far is a map of the United States with a 1910 copyright.

I need to run upstairs and see if either of those big bulbs that I nabbed up in Michigan last summer have that same shape.
That place was a miner's paradise !!!

I think I'll go have some fresh Indiana CORN ON THE COB first though.........
(Is Bob "on the Cob" ?)

James · « **Reply #11 on:** July 21, 2001, 09:54:00 pm »

Hi Tim,

That bulb was indeed marketed as a type S-30, but its technical name would have it classified as an SS-30. Bulb codes are rather confusing, but the first S means it that the part leading up to the major diameter is straight-sided conical blended into an approximately hemispherical crown, and the second S means it has an extended neck portion - just like the difference between a P and PS bulb.

I have an Edison Mazda just like it and I believe the reason for this shape is because this bulb superseded the older designs which employed an S-30 bulb with a skirted base. Skirted bases are expensive and this new bulb was made with a neck portion resembling the old skirt section, that was then dropped down to fit an unskirted medium screw base.

Hope this helps!

James.

Ed Covington · « **Reply #12 on:** July 23, 2001, 11:45:00 pm »

Tim, I put a lamp with a similar shape on ebay back in March, 1999. It was a 100-watt, 115-volt lamp that showed Needham's getter on the supports near the lamp base. The label on the lamp identified it as a "Colonial" Mazda. The maximum bulb diameter was 3-3/4 inches and the lamp length, about 7-1/4 inches. The bulb had "GE National Mazda" etched on it. The getter would indicate a manufacture date of about 1912.

« **Reply #13 on:** July 29, 2001, 02:11:00 pm »

The voltage is easy to explain. Three phase, 480 volts is a common distribution system in industry. Assuming you have a "Y" connected system, if you take any one of the 480 volt phase leads, and the center point of the Y (which is often grounded) you will have 277 volts, single phase. The lighting systems in large installations like factories, stores and office buildings usually operates on 277 volts. With this system, the use of transformers is avoided.
Of course the distribution voltages tend to run higher these days, which accounts for the difference between 275 and 277.