In the year 1883 the Edison & Swan United Electric Light Company, Limited was formed. The lamps manufactured by this company were marketed under the trade name "Ediswan." Collectors of incandescent lamps in the United States seldom come across Ediswan lamps of early vintage but such lamps can be located occasionally on the internet. This write-up describes the terminals or electrical contacts that existed on Ediswan lamps in the year 1893 (Incandescent Lamps, Price List, The Edison & Swan United Electric Light Company, Limited, Section 1, Feb. 1, 1893.)

In the common household incandescent lamps of today the electrical contacts are part of what is called the lamp "base." In 1893, in England, lamps could have bases (or "caps"), or not. Descriptions of terminals (electrical contacts) that existed in that year are given and shown below.

Standard Terminals
Brass Collars to fit Patent Bayonet-joint Holders—B.C.
Edison Screws for Edison Sockets—E.S.
Central Contact for Central Pin Bayonet Holders—C.C.
Side Contacts for Side Attachment Holders—S.C.
Bottom Loop Caps for Spring Holders (strong)—B.L.C.
Bottom Loop for Spring Holders—B.L.

Miniature Terminals
Small Brass Collars to fit Patent Bayonet-joint Holders—Small B.C.
Small flanged edison Screws to fit patent Edison Screw Holders—Small Flanged E.S.
Small Edison Screw to fit patent Edison Screw Holders—Small E.S.
Small Central Contact ti fit Patent Central Contact Holders—Small C.C.

At the top of the compound picture shown to the left below is a special brass collar for 50 c.p. and 100 c.p. lamps. Positioned below the brass collar is a 100 c.p. Sunlight lamp designed for 50-100 volts. Although this type of lamp was fitted with lug terminals, often it was recommended that they be used in B.C. holders. In such a case the special brass collar, which allowed adequate ventilation between terminals and holder, was manufactured. The bayonet cap is used on the collar.

Lamps were available in candlepower values of : 100, 150, 200, 300, 400, 500, 600, 800, 1,000, 1,200, 1,500 and 2,000. The lamps were used for the interior lighting of hotels, restaurants, theatres, workshops, factories, etc. They were used on board ship for cargo lanterns. They also lit railway stations and other applications where a strong steady light was necessary. The lamps are designed with strong copper lugs, which were sealed into glass. They were fit into a lug holder or attached to a flexible cord. The lug holder was made with strong wire prongs, which fit into the curved neck of the lamps.

The lamps at the left are:

Top, left:
Bottom Loops (B.L.) These lamps were made with platinum wires formed into small eyes at the bottom of the lamp. The loops were strong enough to support small-sized lamps. The loops on the 50 c.p. lamp were twisted and therefore fairly strong.

Top, right:
Copper Loop Lamp. These lamps had strong copper loop terminals and were used for use with strong spring holders, by which the vibration experienced in ships, railway trains, mills, etc., was minimized.

Bottom, left:
Bottom Loop Cap (B.L.C.) This was an earthenware cap, where the loops projected out at the bottom, in imitation of the ordinary platinum bottom loops. The cap protected the frail platinum loops of the lamp. These were used on board steamers and wherever there was constant or great vibration.

Bottom, right:
Side Contact Terminal (S.C.) This employed an earthenware cap through the sides of which projected two loops, contact being made by the holder to them. The inconvenience of this design restricted its use to special purpose.

The lamps made with platinum loop terminals are reminiscent of the terminals use on Weston lamps in the United States. Contacts to such loops were usually made with spring loaded hooks.

All lamps are shown approximately full size.

The lamps at the left are:

Top, left:
Small Brass Collar (Small B.C.) This was a very useful terminal of the miniature type for most small sized lamps. It was generally used for candle lamps and wherever a secure but small terminal was required.

Top, right:
Brass Collar Terminal, B.C. This lamp was capped (based) with a brass collar terminal, suitable for bayonet-joint holders. This was an excellent terminal for all ordinary purposes, more of these being used than any other form. Contact was made by means of two little brass plates (not shown in the picture), which left the collar insulated. The Central Contact Terminal was similar, but with only one brass plate, the collar itself forming the other contact.

Bottom, left and center:
Small Edison Screw (Small E.S.) These were candle lamps, without a flange so that the entire terminal was hidden within the holder. Full size.

Bottom, right:
Edison Screw Terminal, E.S. This type of terminal (base) was widely used and found to be very satisfactory. However, such a terminal was nor recommended in applications where constant vibration of the holder was possible. About full size.

Some terminals are not pictured here. One example is a Small Central Contact (Small C.C.), which is similar to one already described, except for size. Most of the terminals were attached to the lamps by means of plaster so at least four days notice was required when ordering lamps, other than B.L., as collars could become loose if used too soon after manufacture.

It is of interest to mention that the bayonet base used in the United Kingdom, and mentioned herein, was developed by Alfred Swan (1835-1923), youngest brother of Sir Joseph Swan. The base commonly used in the United States today, the Edison with black glass insulation, was also a development of the fertile mind of Alfred Swan.