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Author Topic: Bulb ID? Tipped, Westinghouse base, glass anchor supported double loop filament  (Read 6655 times)

Offline Pat Gearty

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Hello,
About Me
I am new to this forum and to the antique light bulb world. My primary collector interest is vintage radios and communication equipment. I grew up in the world of tube electronics and enjoy the warm glow and sound they produce. The little I know about antique bulbs I have learned from this wonderful site and other web resources.  I am looking to members of this forum to enlighten me from your wealth of subject knowledge.

About the Bulb
I have this single light bulb within my collection of radio items.  It sits on display with radio tubes but I know little about it.   
Appearance:
?   Incandescent, tipped, clear envelope
?   5? tall by 2.5? dia.
?   Westinghouse Pin Base. I think the insulator is plaster.
?   Double loop hairpin filament.
?   The filament is supported by two glass anchors at the top of the bulb.
Condition Observations:
?   The envelope is in excellent condition, clear and unblemished.
?   The filament appears to be good.  Resistance measures 1,350 ohms.
?   The metal base has a hole (from arcing?) in the side that does not appear to have impacted the envelope. 
?   The filament lead connection to the base has come free from its solder connection.  To measure resistance I connected directly to the loose wire.
?   The stem has some writing on it that I cannot decipher.  I find no other identifying marks.

I have not tried to apply power to this bulb and do not plan to do so out of fear of damaging it.  I do have both a Variac and a variable regulated DC power supply to use should I choose to do so.

What is it?  Manufacturer/brand, approximate year of manufacture, filament material, physical & electrical characteristics, usage, ??  Any corrections to my assumptions, clarifications, description or additional information you provide would be greatly appreciated.  I would like to present this in my collection with an accurate description.

I learned from this initiative that photographing a bulb is challenging.  Not knowing what views would be important I took pictures from many orientations.    I?ve included two images in this post and provided web links to many more.  If anyone would like original resolution pictures let me know and I?ll email them.

Thanking you in advance for your attention and assistance,
Pat Gearty

Bulb Pictures
https://www.icloud.com/photostream/#A85Uzl7VJJzB5f;e43a8386-c5e2-4d0b-8778-e672d1fd3b43

Stem pictures.  This was my attempt to read the writing there-on.
https://www.icloud.com/photostream/#A8Grq0zwq5fyC

These photos use Apple iCloud photo streaming.  On a non-apple PC:
1.   Click on the URL to go to the web page of photos.
2.   On the webpage, click any photo to view it larger.
3.   Do any of the following:
?   Click the forward and back arrows to navigate through the photos manually.
?   Click the Slideshow button (top right of screen) to view slideshow.
?   Click the Download button (top right of screen) to download a photo.

Pat Gearty

Offline Lampje

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  • Posts: 21
  • Passionated Light Bulb Collector
Hi there,

Does it has a carbon or a tungsten filament?

Offline Pat Gearty

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Filament type was one of the questions I asked in the original post.  I do not know what the filament material is and would not know how to identify it.  ~ Pat
Pat Gearty

Offline PCris

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  • Posts: 21
Hi Pat,

I do not consider myself an expert on antique bulbs, and I'm always interested in learning everything I can about them which is why I am a member of this forum. I am a collector of antique bulbs from the mid-1880s to the early 1920's, an interest I've had since I was in elementary school many years ago. So, I'll offer my two-cents worth based on observations, and hopefully others will add to this to help complete the picture for you, as well as for other early lighting enthusiasts.

First of all, what a rare and interesting lamp! Your photos are outstanding.

As far as the filament, I am certain that it is carbon of some sort. Those hairpin types would be unlikely to be tungsten which has its own distinctive forms. Also, it appears that the attachment of the filaments to the lead-in wires is carbon paste which has been the traditional way of attaching carbon filaments since the 1880's.

My best guestimate is that this dates from the early 1900's. You correctly ID the base as the Westinghouse pin type. This base was rapidly becoming obsolete by the 1900s in favor of the Edison screw base. However, WH bases were still produced into the early years of the 20th c. The reason I think this may be an early 20th c. lamp and not late 19th c. is that from the pictures it appears that the base is secured to the glass envelope with a dark colored adhesive, not plaster which would be white in appearance. In 1901 a water-proof cement was developed which quickly replaced the use of plaster for this purpose.

For this next bit I'm skating on thin ice, but I'm not sure what the lead-in wire material is going through the stem press. Earlier bulbs used platinum through the press with less expensive wire welded on to complete the connection to the base. From the pictures it looks to me like it may not be platinum, but that's just a guess on my part, but if correct in this, that could indicate a little later date of manufacture.

I think the insulating material in the base to be porcelain because of the way it extends slightly beyond the end of the brass part with a slight bevel. The WH-based lamps in my collection that are like this are porcelain; the plaster ones I have are all flush with the end of the base.

One of the outstanding features of this lamp is the double hairpin filament configuration. It's too bad that a paper label doesn't still exist on the exterior of the envelope (these often don't survive) as that would give you a rating and possibly even who the manufacturer was.

The most distinctive part are the anchors. This kind of arrangement, undoubtedly more difficult to manufacture and therefore more expensive, was a feature designed for lamps to be employed in situations subject to vibration, such as mills, factories and trains. Lamps with this feature are hard to come by, and therefore quite attractive to collectors.

Well, as I said, my two-cents worth. I hope others weigh in. Definitely a really neat lamp. Thanks for sharing this in the forum.

Best Regards,

PCris

Offline Pat Gearty

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PCris,

I appreciate your detailed and highly informational response.  You considerably underrate it at only two cents!  Thanks for taking the time to study the pictures and share your knowledge and experience.   It appears that the number of bulb collectors is relatively small and this forum is a wonderful community for them and especially for those of us with a new interest.

Thanks,
Pat

Pat Gearty