The Lighting Time Table

To read the entire tutorial, you can just click on the first link and then continue to the next section at the bottom of each page. Or, you can select links below of interest to you.

PRE 1900 SECTION

Overcoming Obstacles
About Early Electric Lighting, Generators, Arc Lamps, The First Edison Socket, Menlo Park, etc.
The First Fixtures
About The Start Of The First Incandescent Lighting Fixtures
Light Reflection
About Early Light Bulbs And Candle Power vs. WATTS
Edison-Bergmann
About Sigmund Bergmann And The Start Of Bergmann And Company Lighting Fixtures
Lighting Break Down
A Quick Break Down Of Different Lighting Time Periods
Styles 1881 to 1884
Bergmann Fixtures And Styles
Other Pre-1888 Styles
About Early Companies That Sold Lighting Systems And The Fixtures That They Sold With Their Lighting Systems
The U.S. Elect. Co.
The United States Electric Company History And Early Items
The Brush Elect. Co.
The Brush Electric Company History And Early Items
Thomson-Houston
The Thomson-Houston Electric Company History And Early Items
Westinghouse
About The Westinghouse Manufacturing Company History And Early Mergers
Mid 1880's Styles
About The Start Of Electrical Supply Houses and how new lighting styles came about
Pre 1900 Sockets
About Early Light Sockets And How To Tell The Difference
1887 New Items
1888 New Items
1890 New Items
1891 New Items
1892 New Items
1893 New Items
1894-1896 Items
1897 New Items
1898 New Items
1899 New Items
Above are catalog items sold in different years. There is no space to duplicate items, so only new and unique items from each year are shown. You would need to view the catalogs for yourself to be complete as I am only highlighting items. You can view catalogs here.

EXTRA INFO
Victor Shade Holder
About The Victor Shade Holder, Atwood And The Standard Holder

I.P. Frink 1899 Items
About Frink & Wheeler
New Wheeler Inverted
Three Links About Mirror Reflector Manufacturers And Their Items And History.
Wheeler Reflector Co.
NEW - A history of The Wheeler Reflector Company and tips on how to tell if mirror has been replaced on a shade

Early Desk Lamps
Some Help In Telling Them Apart

Vitrite And Luminoid
About The Vitrite Holders And Early Vitrite History

Brush-Swan Holder
About Brush-Swan Shade Holders

Cord Balls
My cord pendant adjuster project, as well as a good history about them.

POST 1900 SECTION

About 1900 Styles
This section covers a basic into into the 1900 section covering information about the 1899 transition, electrical code changes, lighting influence, sharing and licensing of patents and then into the new section of electrical specialty manufacturers,

Electrical Specialty Manufacturers
Harvey Hubbell
This section covers some early history periods of pre Hubbell-Grier, Hubbell-Grier, Harvey Hubbell, Hubbell Company. It also covers a number of items that helped change lighting styles,

Benjamin
This section covers some early history periods for the Benjamin Electric MFG. Co, as well as a small section on Dale and The Federal Electric Company
Dale
Federal Electric

This post 1900 section continues to be under current construction

Please Check Back.

ABOUT THE LINEUP
The No. 2 Bergmann socket is part of a lineup. A socket line up simply means that the socket design was carried through different companies and through different periods of time. In this case starting as an Edison/Bergmann invention and then living on through later company mergers.

The lineup shown below for the acorn socket is mostly the joint research between myself and Adam Allerhand, which we started working on sometime around January of 2008. Please check back from time to time for updates to this section. If a future update is ever added to this page, it will be added in the format of a red dated headline to make it easy to find.

Since the No. 2 (acorn socket design) extended through many years, we will cover the entire lineup of acorn sockets and then move on to the Bergmann No. 3 socket, which would be the next oldest socket after the first acorn socket.

ABOUT THE FIRST ACORN SOCKETS
One of the most popular Bergmann sockets of the early days was the acorn socket.
It was an early design that held to the test of time. During the history of this socket, only a few small changes were made in the design which we cover in detail below.

The acorn was the standard socket used for fixtures that did not require a method to turn the fixture off and on.
Thus, the acorn is and always has been a keyless socket.

THE DATING DILEMMA
The acorn is one of the hardest sockets to date and keep track of, because of its many slight changes with no real way to document exactly when those changes took place. Most of this problem was caused by catalogs using old illustrations. The worst case examples of this would be found in the Bergmann & Co. catalogs (more about this topic here), which show the same illustrations in 1889 (their last year of business) as they did in their early 1883 company catalog.

As you see from above, the catalog illustrations did not change until after the first merger took place. The Bergmann catalog shows the same socket illustration until they merged into Edison General Electric in 1889. EGE then uses the same illustration in their company catalog, but finally updates the image in their September 1891 catalog!

The problem here however, is that between 1883 and 1892 there were FIVE different acorn styles!

Also note that electrical supply catalogs of the era did not normally make their own illustrations of the items that they sold. They took illustrations from other supply catalogs, magazines, trade catalogs, etc. This is another dilemma in itself as seen in the capture above of the 1891 Gate City Electric Company catalog image, which appears to be selling the no. 1 acorn in 1891.

I should mention that most times catalogs are a great dating tool. I am only pointing out a worst case scenario here, in order to help keep you from possible future mistakes.

THE ACORN PATENT
The acorn patent was applied for on October 9th 1882 and approved on February 12th 1884. Sigmund Bergmann is listed as the inventor and the patent was assigned to Bergmann & Co. The patent was given patent no. 293,552.

Also, because these later changes to the socket (talked about above) did not change the claims that were in the patent, no new patents needed to be filed to document the changes.

We are however able to give a fairly accurate lineup in the order that they were produced, based on materials used, styles of ribs and early pictures or illustrations that are dated.

Noteworthy is the fact that the acorn socket was Bergmann's first socket to use all fiber insulation (without the inclusion of wood). Sometime around 1890, porcelain started being used.

Please also note the fact that there could be other (so far unknown) later variations missing from our lineup of acorn sockets.

Acorn No. 1 - "The Bergmann Ribless Acorn"
This first acorn was ribless as you can see from the smooth tube above the collar. It is also shown without a rib in the patent, as well as the circa 1883 Bergmann catalog.

Also, note in the patent and catalog illustration, that the cap on the first ribless acorn, did not yet use the heavy threaded cast piece of later acorns. This gives this first acorn a more unique look then those to come after it.

So far we know that the first acorn existed, when the patent was applied for in October of 1882. However, because previous Bergmann patents were not allays applied for right away, we can not rule out it existing prior to this date. It would not be logical for it to have existed before February 25th 1882 since this was the patent date for the center contact.

We can also (more then likely) rule out the ribless design being manufactured after August 13th 1883, since we know that a design with a rib had already been invented and used in some early patent illustrations. One of these illustrations is shown below taken from patent no. 307,759 which was for for a cigar lighter (assigned to Bergmann and Johnson). This patent proves that the next version of the acorn existed in August of 1883. It shows not only the rib existing, but the non-tapered cap as well. This is clearly shown in the compared the acorn and lighter patents shown above on your right.

Also note that the cigar lighter was likely already being manufactured and sold before the patent was applied for, because as shown below in the real example, it is still ribless.


Note that the photo of the ribless cigar lighter shown above was taken by David Christian (a member of our forums), which was on display at the Edison Winter Estate Museum in Fort Myers Florida.

To identify the no. 1 acorn at a glance, simply look for the missing rib and the tapered cap.
I should mention that I have found one later sleeve without a rib (which I know very little about). When seeing a ribless acorn, it might be worth making sure that it uses rectangle screws and uses the first cap design. Another thing to be sure of, would be that it uses a beveled sleeve which is explained further below for the no. 2 acorn.

Acorn No. 2 - The First Bergmann Acorn With A Rib
The second Bergmann acorn is much like the first design, with only a couple minor changes. These changes were documented above, the first of which was the new heavy cast brass cap bushing.

The new cap bushing was inserted into the cap and then held with a ring of solder as shown in the picture on the left. This new style bushing will be seen on other newer acorns and sockets, as we work through this and other sections. The only real change to the bushing will be a crimp along with the solder, and much later much later (around 1890) when a new crimp method is used without the use of solder.

The other change talked about above, was the addition of the ornate rib on the shell, which is shown in the picture above on your right.

The rib will go through many changes, as you will see as we step through this section. Some of these changes will even solely designate an entire new acorn version. While it is not documented, it is believed that changes in the rib placement took place to make room for new designs of shade holders. Later, when the ornate rib is changed to a larger plain style, it was likely done to conform to other socket designs that were using newer style clamp on holders above the rib. It is noteworthy though that Edison shade holders (using the collar attachment) were almost always used with these sockets. The plain rib was only a cosmetic style. Acorn sockets were not designed to use a shade holder above the rib, as other sockets of the era were.

I will now cover the items that did not change.
This will help to identify not only this No. 2 acorn, but also the No. 1 acorn at a glance (since after this acorn version noticeable changes take place that only these two acorns share in common).



If you are looking down into the socket tube at the center contact, take notice if there are NO screw holes in the fiber plate. If there are no holes (as seen in the picture on your right), then it is a No. 1 or No. 2 acorn innard. As shown in the illustration above, newer acorns use longer base plate screws. This new method (used on acorns after these) required holes to be drilled into the fiber plate for the screws to thread into. These threaded holes come through and show on this opposite side of the plate. Since there are no holes in the picture shown on your right, it would need to use the first method of securing the plate which was the side soldered pins.

Compare the picture above on your right, with the picture below of the No. 3 acorn center contact to notice the difference.

As for dating, we only know that this socket likely already existed on August 13th 1883. This is because it was used in patent no. 307,759 as an illustration for a cigar lighter, that was assigned to Bergmann and Johnson.

Some quick notes on the pictures shown above: (1.) Both of the innards shown above are made from a white (paper like) fiber material, of which one is discolored. All other Bergmann acorns that I have seen are made from red fiber. (2.) At this time there is no real way of knowing which of the no. 3 shells came first (short or long sleeve). (3.) The long sleeve socket came to me as a shell only (no innards) and filled with an extra innard that I had in stock (so, it is not original to the shell). (4.) The bottom pictures of the two sockets compared, makes it appear that one socket is larger then the other. This is only an optical illusion. (5.) At this time there is no dating documentation for this socket or its innards.

December 30th 2010 (Added rotary patent info and links)
There is not that much dating information about this acorn version. We only know that it was used prior to the porcelain version shown below as no. 5. It is likely that this plain rib acorn started about the same time as the FAT Bergmann shells. At this time we can only document the start date or first use of the FAT shell design to the first rotary switch patent, which was applied for on June 2 1888 (read here and also here for more info). We also have documentation to show that acorn no. 5 (below) was being used during 1891. In this light it could be safe to at least assume that this acorn stopped being used by 1890/1891. Noteworthy is the fact that porcelain innards would fit this shell, so left over inventory of these shells could had been used (though I have not seen any of these shells with porcelain innards yet).

December 30th 2010
Also noteworthy is the fact that we have also found porcelain / fiber transitional acorn no. 4 sockets. These are of the same design as shown above, made of half porcelain and half fiber. How this fits together with the acorn no. 5 migration shown below, I do not know at this time. I will however take a much closer look at this when I research this and post up the new information and pictures which will be right here in this area soon.

A special thanks goes to David P Christian from our forums who provided the information and pictures of the samples I will be adding.

Added July 19th 2009 (Acorn No. 4b)
The acorn shown above described as "acorn no. 4 with long sleeve", has a slightly different sleeve (hereafter referred to as acorn 4b).

On close examination, you will notice that the rib is a bit thicker and extends just a bit more towards the collar.
The sleeve measurement also measures larger.

This is likely a transition between acorn no. 4 and acorn no. 5. As you will notice from the sleeve pictures below, this acorn 4b sleeve shares the rib and rib placement of the no. 5, while sharing the similar top bevel as acorn no. 4.


A thank you goes to Adam Allerhand for providing the 4b acorn sample.

The no. 5 acorn has a real unique shape, that is not easily noticed from the photos shown above.

This acorn was most obviously made for porcelain innards. However, because of the close timeline of the conversion from fiber to porcelain (1890/1891), you can find these acorns with fiber innards (just as the one shown above on your left).

The outer diameter of the shell is over 43 millimeters!
A cap from the no. 3 will not fit this shell. If you try, you might be able to get an uneven or tight fit with a no. 4 cap.

Since the top of the sleeve has been greatly widened, it has almost completely lost the more bulbous (bulgy) shape of the acorns that came before it. The catalog illustration shown on your right shows a good depiction of the almost completely straight line angle from the cap to the rib.

In 1889 Bergmann & Co. was merged into a new company called Edison General Electric.
This no. 5 acorn was the design that was used during the entire life of the EGE company (1889-1892).

As also shown below, G.E. used this acorn design from 1892 until 1897

The next merger that took place was in 1892, at which time Edison's electrical companies were taken over by the Thomson-Houston company. Thomson-Houston merged the newly owned Edison companies as well (as their own electrical companies) into a new company that they formed called "General Electric". During this merger, stock holders of the old companies were paid and the new company was basically Thomson-Houston with a new name. General Electric, now owned Edison's patents as well as his name rights for electrical items.

I note this strongly for those that like to think that they are strong personal "Edison" or "Bergmann" fans.

When it comes to these last areas, take note that "Bergmann" (the person) had nothing to do with these electrical items (starting with the date of the EGE company). ALSO, "Edison" (the person) had nothing to do with these electrical items (starting with the date of the General Electric Company). After this 1892 date; when you see the Edison name being used by General Electric, it is simply Thomson-Houston wearing their Edison Halloween mask.

The first acorn that G.E. designed, was the one shown and announced in the G.E. bulletin shown above on your right and also described below.



Noteworthy is the fact that I have seen one mica acorn that used square nuts.

Note that another later version of this no. 7 acorn existed after this, without mica under the center contact. This acorn would date from about 1910 until 1919.

As a general rule, manufacturers used mica under the center contact from the years 1900 until 1910 at which time mica began to disappear from new items. This acorn no. 6 was offered in G.E. supply catalogs as catalog number 66225 starting in 1897. It was changed to catalog number 50750 in 1904 (the next catalog, now this no. 7 acorn), until 1919 at which time it was removed from their catalogs and no longer offered.

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