The eye-piece employed on the South equatorial must also receive a brief notice. It will, of course, be obvious that the full glare of the sun has to be greatly mitigated before the eye can view it with impunity. The light from the sun falls upon a piece of transparent glass inclined at a certain angle, and the chief portion of the sun's heat, as well as a certain amount of its light, pass through the glass and are lost. A certain fraction of the light is, however, reflected from the glass, and enters the eye-piece. This light is already much reduced in intensity, but it undergoes as much further reduction as we please by an ingenious contrivance. The glass which reflects the light does so at what is called the polarising angle, and between the eye-piece and the eye is a plate of tourmaline. This plate of tourmaline can be turned round by the observer. In one position it hardly interferes with the polarised light at all, while in the position at right angles thereto it cuts off nearly the whole of it. By simply adjusting the position of the tourmaline, the observer has it in his power to render the image of any brightness that may be convenient, and thus the observations of the sun can be conducted with the appropriate degree of illumination. But such appliances seemed on this occasion to be a mere mockery. The tourmaline was all ready, but up to one o'clock not a trace of the sun could be seen. Shortly after one o'clock, however, we noticed that the day was getting lighter; and, on looking to the north, whence the wind and the snow were coming, we saw, to our inexpressible delight, that the clouds were clearing. At length, the sky towards the south began to improve, and at last, as the critical moment approached, we could detect the spot where the sun was becoming visible. But the predicted moment arrived and passed, and still the sun had not broken through the clouds, though every moment the certainty that it would do so became more apparent. The external contact was therefore missed. We tried to console ourselves by the reflection that this was not, after all, a very important phase, and hoped that the internal contact would be more successful.