Carbon Arc Magic Lanterns or Balopticons
The magic lantern above is the Model D Balopticon with a hand fed electric carbon arc lamp.
The 1927 Bausch & Lomb Optical Company catalog describes it as follows:
“The Model D Balopticon, which is constructed on what is known as the optical bed type of construction, is an ideal instrument for use by science teachers or in any laboratory, as it is made to accommodate many accessories used in such work. An accurately milled bed of lathe type is supported by feet at either end, those at the front being provided with leveling screws. To this optical bed the lamp house containing, the arc and the standards supporting the different accessories are attached by means of clamping blocks. These standard may be adjusted along the bed to any position, and the act of clamping fixes them rigidly in optical alignment
“The triple condensing system and water cooling cell, with which the Model D is equipped, make it a perfect outfit for lantern slide projection.
“The large, light-tight, housing meets the most rigid requirements of the Boards of Underwriters, and is particularly recommended where a part of the audience is seated back of the lantern and for use with arcs of high amperage.
The catalog goes on to list its specifications in the following manner:
“Base—consists of cast iron support of 6-inch spread, front and back, supporting optical bed 2 ¾ inches in height; front support provided with elevating screws.
“Optical Bed—Of lathe type, carefully planed, accommodating supports for different parts which may be adjusted as desired and rigidly clamped; measures 19 ½ inches in length and accommodates projection lenses up to 15-inch focus; it is furnished with 25-inch optical bed accommodating projection lenses from 18 to 22-inch focus.
“Lamp House—Sheet metal, fitted with our special, patent, light-right ventilator and provided with tow observation windows; measures 13 ½ inches long, 15 inches high and 7 ½ inches wide, light-tight, constructed of double walls with air space between and provided with large light-tight door on the side—conforms to the most rigorous requirements of Boards of Underwriters.”
“Illuminant—Hand-feed lamp for direct or alternating current.
“Condensing System—Our triple system in patent, ventilated mount; provided with water cooling cell; diameter, 4 ½ inches.
“Slide Carrier—Our double carrier, No. 4430, with elevating device.
“Projection Lens—Our Balo lens with rack and pinion adjustment.
“Dimensions—Length, extended, 32 inches without lens; height, 15 inches.
The booklet goes on to offer a substitute for the No. 4430—“the quick-changing slide carrier, No. 4449, giving a dissolving effect.” .
For additional money, thick brochure also offered two different vertical attachments. The Model 4136 Vertical Attachment, selling for $75.00, included a separate projection lens and condenser to permit instant inter-change with lantern slide projection. However, the No. 4290 Vertical Attachment designed for the Model D Balopticon Arc light sold for $30.00. The 63-page catalog offered a reduction in price of $6.00 if a 1,000 watt Mazda lamp was selected instead of the hand-fed arc lamp.
The paragraphs with their descriptions ran thus:
“For the projection of transparent objects which must be maintained in the horizontal position two attachments are available. No. 4290 is attached to the slide carrier support by removing the bellows and substituting in the sliding ways the prism-shaped metal box which contains a reflecting mirror. No. 4136 is far more convenient and affords a much wider range of usefulness because one can change instantly projection with this attachment to the use of lantern slides and vice versa.
“The instrument has a dark chamber supported by two standards which fit the optical bed and are provided with clamps. Within this dark chamber is the reflecting mirror, controlled by a conveniently placed exterior lever. When the mirror drops to the 45° angle, it reflects the light up through the vertical attachment.”
Above, we see the No. 4452—4 ½ ampere rheostat (resistive inductor) offered for arc lamps by Bausch & Lomb. Rheostats—although there are other means—are often used with carbon arc lights to limit the current in their circuits. Otherwise, the carbon arcs would essentially see short circuits across their gaps and increase in current till their circuit wires burned up—thereby damaging and extinguishing the lights.
Here we see on the left the 15-Ampere Bausch & Lomb Rheostat No. 4450 and 15-35-Ampere Rheostat, No. 4456, on the right. The B & L Catalog states:
“With every arc lamp there must be used a rheostat, selected according to the voltage available and the number of amperes required.
“We construct our rheostats to meet the strictest requirements of fire boards and underwriters, and they have been approved by the National Board of Fire Underwriters’ Laboratory of Chicago. The wire in the resistance coils has practically no temperature coefficient and will not deteriorate with frequent heating and cooling. The cases are of perforated metal, thus providing for the freest possible air circulation among the coils. There are no exposed contact points, and every means of insuring safety has been taken advantage of.
“The coils in rheostats of 15 amperes capacity and over are wound on asbestos board strips to prevent sagging or possible contact between coils. The coils in the 4 ½ ampere rheostats are carried on porcelain spools.
“The 4 ½ ampere rheostats can be used satisfactorily with the electric wiring usually found in private houses, connecting with the ordinary lamp socket. Those of higher capacity generally require special wiring.”
Below is a recent photograph of the type of plug, switch, and rheostat terminals used with magic lanterns and ordinary lamp sockets and carbon arc rheostats of the 1920’s. In the photograph below it, we see that they are attached to a vintage Bausch & Lomb Balopticon, which we have here on hand. The two round terminal lugs connect nicely to the number No. 4452 Rheostat illustrated and discussed above.
Notice that this Bausch and Lomb magic lantern uses a different arrangement for manually controlling the carbon arc light. The two cold ends of the carbons can be seen sticking out of the rear of the projector, from the convex metal plate with the round, dark glass used to view and adjust their fiery ponts inside. The special glass prevents the arc's Ultra Violet radiation from damaging the operator's eyes . The control on the left adjusts both carbons inward or outward simultaneously, to maintain the necessary distance to maintain a bright arc in the Balopticon.
This model of Bausch & Lomb Home Balopticon is not listed in the 1927 catalog, and its name plate below provides no date.
However, judging from a vintage Bausch & Lomb advertisement for the same type of slide projector in a 1909 publication, we can safely conclude that this magic lantern is nearly a hundred years old.
Above is Larry Brian Radka's photograph of an actual image produced by a Baush & Lomb Balopticon or Magic Lantern purchased on Ebay
This page was last modified on Tuesday, January 19, 2016