A large T-square of light wood will be useful to enable the observer to judge whether the screen is properly situated in the last respect.
We wish now to direct the tube towards the sun, and this "without dazzling the eyes as by the ordinary method." This may be done in two ways.

We may either, before commencing work--that is, before fastening our elastic cord so as to exclude all light--direct the tube so that its shadow shall be a perfect circle (when of course it is truly directed), then fasten the cord and afterwards we can easily keep the sun in the field by slightly shifting the tube as occasion requires.

Or (if the elastic cord has already been fastened) we may remove the eye-tube and shift the telescope-tube about--the direction in which the sun lies being roughly known--until we see the spot of light received down the telescope's axis grow brighter and brighter and finally become a _spot of sun-light_.

If a card be held near the focus of the telescope there will be seen in fact an image of the sun.

The telescope being now properly directed, the eye-tube may be slipped in again, and the sun may be kept in the field as before.
There will now be seen upon the screen a picture of the sun very brilliant and pleasing, but perhaps a little out of focus.