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 results shown in the middle, we should say that the polarization is complete. If we get a pair as shown at the bottom, we should say that it is only partial. The actual pair I got in Egypt in 1905 is shown in Fig. 80. My conclusion is that there are a large number of solid particles in the corona, because there is a great deal of polarized light;

and other astronomers have found the same thing. And now, since you have listened so patiently to this tiresome explanation, I should like to show you that polarized light can give us some very pretty colours, which I am sure you will enjoy seeing.

[The lecture concluded with an exhibition of polariscopic effects from the magnificent collection of apparatus at the Royal Institution.]