School Micro Projector. 
The school micro projector is a simple and self-contained apparatus suitable for use in schools 
and teaching establishments, and capable of showing pictures up to 4ft. 6in. There is a 
minimum amount of adjustment required for its use, as once the apparatus has been set up and 
connected to the supply, all that has to be done is the necessary focussing of the specimen upon 
the screen. 
The instrument is soundly constructed throughout. The base is heavy and rigid with handle 
for lifting. On to it is fitted the main tube of the projector with adjustment for raising, lowering 
and rotating. The projector has a projection lens and two supplementary lenses of different 
powers. Thus four magnifications are provided. The lowest is obtained with the projection lens 
only, the second and third with the supplementary lenses A and B and the fourth by using the two 
supplementary lenses together. The following table gives the magnification and circle of illumination 
working at a distance of 10 feet from the screen :— 
Magnification Circles of 
| illumination 
Projection lens only ape sis es 100 | -2ehte (ume 
Projection lens and supplementary lens A Bes aes se 150 | 3 ft. 6 in. 
Projection lens and supplementary lens B : ee se 200 Shite Osim 
Projection lens and supplementary lenses A andB.. oor 275 | 4 ft. 6in. 
} 
The specimen is held in a spring stage. The lamp is contained in a well ventilated housing and 
has adjustments for its centration. A smooth and accurate focussing motion is fitted. 
The lamp is either a 12 volt 48 watt projection lamp or a 50 volt 200 watt. The latter gives 
a very intense illumination and as, in projection, the best results are obtained with the greatest 
intensity of light, it is this type we most strongly recommend. 
No. 2612. Micro projector with 48 watt lamp... a Say ses sie seep) EO) 
No. 2612A. Micro projector with 200 watt lamp ... ; UP Ao 
No. 2606. Cooling trough. This can be supplied to either No. 2612 or No. 2612A, 
and we recommend it to be supplied in the first instance, otherwise 
if ordered subsequently the projector must be returned to us for the 
necessary fitting ee oth ee a ie Zz 0 
No. 2614. Projector lamp 48 watt for replacements aa aa ose oer sis 0 4 
No. 2614A. Projector lamp 200 watt for replacements Ll 
No. 2613. Resistance, adjustable, for voltages 100—250 direct current. or ae 2 5 
No. 2616. Transformer for use on alternating current, voltages from 200—250, 
50 periods, output 12 volt, 4 amps. (for No. 2612) _... ae 3 6 0 
No. 2617. Transformer as No. 2616 for use on voltages 100 to 120, 50 periods 3 
No. 2618. Transformer for use on alternating current, voltages from 200—250, 
50 periods, output 50 volt, 4 amps. (for No. 2612A) ae ve she 4) 1? 16 
No. 2619. Transformer as No. 2618 for use in voltages 100 to 120, 50 periods as AT 2G 
107 
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