Scientific illumination for schools / Holophane Limited.

Date:
1921
Catalogue details

Licence: Public Domain Mark

Credit: Scientific illumination for schools / Holophane Limited. Source: Wellcome Collection.

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    high efficiency in the percentage of the total light which is made available in downward directions. The action of this unit is well illustrated in Figure 4. Fig. 4. Diagram showing the internal action of the Holophane Reflector- Refractor Unit. A large proportion of the light sent downward by the upper reflector, passes through the opening below. The lower part of the unit, known as a Refractor, acts as a protection for the eyes and also directs a large portion of the light at a useful angle to the desk surfaces. In the smaller sizes the two parts of the Holophane Keflector- Refractor are mechanically fused together, thus making the unit the equivalent of one solid piece. Its relatively small size is a feature, but in spite of its small dimensions the bottom opening makes it possible to renew or clean the lamp conveniently. The slanting walls of smooth glass tend, furthermore, to prevent accumulations of dust and dirt which insure the system against a rapid depreciation from this cause. For classroom lighting, therefore, the Reflector- Refractor unit is particularly recommended, being efficient and glare subduing. These features make it a most valuable auxiliary for school lighting systems. Holophane Excellites. The completely enclosing feature of this device is shown in Fig. 3, page 9. The unit consists of two sections which are fastened together mechanically, thus making it one piece in its essential feature. The upper portion is an efficient Holophane Reflector so designed as to reflect a large proportion of the total generated light to the under bowl. The latter acts as a diffusing medium in reducing glare, and at the same time distributes the light effectively. Holophane Excellites are especially suited to large interiors with high ceilings, and where the outlets are relatively far apart, as, for example, in large halls, etc. For rooms with lower ceilings, the open Holophane Reflector or the Holophane Reflector - Refractor are preferable types to use.
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