53

To Polish the Silvered Surface.

Make a couple of polishing pads by filling two pieces of very soft wash-leather about six inches square loosely with cotton wool, and tying them into balls (Fig. 27). Gently remove any dust that may have settled on the film with some loose cotton wool, and then go over it with one of the pads in small circular strokes for about 5 minutes or more (Figs. 28 and 29). This will consolidate the film and fit it for polishing. Spread a little of the finest rouge on a sheet of writing paper, and impregnate the other pad with it Go over the film with

Fig. 28.

Fig. 29.

the rouged rubber, using the same circular strokes until it is perfectly polished. Never commence with the rouged pad, as the surface may be injured. When once the film has been consolidated it will remain so, and can be repolished many times with the rouged pad should it get tarnished. The pads should be kept from dust in wide-mouthed bottles for future use. With care the film will last for a long time, especially if it is not allowed to get damp, and consequently the mirrors should never be brought uncovered from the cold air into a warmer temperature.

A small box or bag containing some quick-lime, kept in the tube of the- telescope when not in use, will help to absorb all extraneous moisture.

A lens may be supported in the solution by twisting a piece of copper wire round its circumference, and then silvered and polished in the same way as the speculum.

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