On Friday the 23d we saw the Peak of Teneriffe bearing W. by.  S. 1/2 S. and found the variation of the compass to be from 17 deg. 22’ to 16 deg. 30’.  The height of this mountain, from which I took a new departure, was determined by Dr. Heberden, who has been upon it, to be 15,396 feet, which is but 148 yards less than, three miles, reckoning, the mile at 1760 yards.[68] Its appearance at sunset was very striking; when the sun was below the horizon, and the rest of the island appeared of a deep black, the mountain still reflected his rays, and glowed with a warmth of colour which no painting can express.  There is no eruption of visible fire from it, but a heat issues from the chinks near the top, too strong to be borne by the hand when it is held near them.  We had received from Dr Heberden, among other favours, some salt which he collected on the top of the mountain, where it is found in large quantities, and which he supposed to be the true natrum or nitrum of the ancients:  He gave us also some native sulphur exceedingly pure, which he had likewise found upon the surface in great plenty.

[Footnote 68:  It is not said by what means Dr H. ascertained the height of this peak, and one may safely call in question his accuracy.  In the table referred to in a former note, its height, as measured by the barometer, is stated to be 12,358 English feet, being nearly 10,000 feet lower than that of Chimborazo, the highest summit of the Andes, which is estimated at 21,440.  But there is a good deal of contrariety in the statements of the heights of mountains.  The following quotations from Krusenstern’s account of his voyage will both prove this, and at the same time give the reader some lively conception of the magnificent effect of the Peak.  “At half past six in the morning we distinctly saw the island of Tenerifle, and at seven the pic cleared itself of the clouds in which it had been enveloped until then and appeared to us in all its majestic grandeur.  As its summit was covered with snow, and was extremely brilliant from the reflection of the sun, this contributed very much to the beauty of the scene.  On either side, to the east and west, the mountains, which nature seems to have destined to sustain this enormous mass, appeared gradually to decline.  Every one of the mountains which surround the pic, would be considerable in itself:  but their height scarcely attracts the attention of the beholder, although they contribute to diminish the apparent size of the pic, which, if it stood alone, would be much more striking,” “At six the next morning, (this was the second morning after leaving Tenerifie) we still saw the pic from the deck; it bore by compass, N.E. 15 deg. 3O’, that is, allowing for the variation, which is here 16 deg.  W.; N.W. 0 deg. 30’.  At noon, we had an observation in 26 deg. 13’ 51” latitude, and 16 deg. 58’ 25” longitude.  Between six in the morning and noon we had lessened our latitude 21’ 53”, and increased our longitude 19’ 15”.