Jameson tells us that it took him six weeks to survey Orkney geologically, and that the journey was the most uninteresting he ever made ; his journal, indeed, is little more than a record of disappointments. Jameson's statement, so far from concealing, disclosed an indubitable fact, that to relieve the tedium of the hammer through weeks of wandering, some impulse,—some attraction of a different nature must be associated with it. Jameson himself showed that such attraction was present with him, though he seems to have put a restraint upon himself as regards the alluding to it.

When we look at a collection of crystals we see that they can be divided into groups according to their symmetry. Thus, one group the members of which form the cubical system, have a symmetry in three directions at right angles to each other ; that is to say we shall find similarly arranged planes at the extremity of three properly chosen axes. In other groups the symmetry is not so perfect. Thus, in the tetragonal system we find that the symmetry in the direction of the principal axis is different to the symmetry in the direction of the lateral axes.

The behaviour of tin under varying circumstances has frequently attracted the attention of chemists, and several authors have concluded that it is capable of assuming at least two different crystallographic forms, only one of which, however, has been thoroughly investigated. Since Miller described the beautiful pyramidal crystals of tin obtained by galvanic deposition from a solution of its protochloride, the anomalous appearance of those obtained in the dry way has often been remarked upon. Brooke obtained octagonal needles on slowly cooling molten tin and pouring off the fluid part. Pajot in a similar manner obtained rhombic prisms. Stolba obtained quadratic plates, whilst Breithaupt saw tin crystals, from Cornish smelting furnaces, which had the form of short hexagonal prisms (Miller considered them to be Cu Sn2). Lastly Rammelsberg inferred from the varying specific gravity that a not yet determined dimorphic form existed.

In my preliminary notice of this substance, I stated, upon the authority of Dr. Aitkin, that it had been supposed that it very possibly had at one time been used as a pigment in Inverness; a eolourist there manufacturing a paint the nature of which he kept secret.

In re-arranging lately, a number of chemicals which had been made over to me in 1856 by my predecessor, Mr. Connell, I found a bottle with a powder of the same tint, but somewhat darker than the washed Abriachanite. The label of this bottle bore on it "Ultramarine made in 1841, by Murdock Paterson, dyer in Inverness."

I have not yet had an opportunity of analysing this powder, which may be merely abriaehanite darkened by simple treatment with an acid.