Royal Observatory Greenwich | 1859 April 23
My dear Sir
I am much obliged for your sending me your lecture upon Glaciers,1 which has been here three or four days.
In the interesting Lower Glacier of Grindelwald2 to which you allude with so much pleasure, there is one appearance of which I should be glad to have the explanation. In descending from the Eis Meer, you probably remember how that first the ice is broken by enormous cross-crevasses: that then the crevasses become a little curved, then convexly upwards, that the great vertical laminæ3 then begin to crack across a little, that then the [crosses] break the ice into blocks, that these blocks become pyramidal pinnacles, to all appearance perfectly homogenous, and that this state is succeeded by a plain solid glacier state completely riddled with horizontal veins.
Now the thing which I want to have is, how these horizontal veins are formed, because, in the state which immediately precedes them, there is not (as far as my eyes could see) a single vein.
I wish I could have two photographers at command, who, acting under my instructions, and separated to such distances as I should indicate, would take pairs of stereoscopic plates4 at different parts of the path and at different places on the Glacier.
I am, my dear Sir, | yours truly | GB Airy
RGO Archives/MS.RGO.6/378
your lecture upon Glaciers: likely refers to Tyndall’s paper, ‘On the Veined Structure of Glaciers; with Observations upon White Ice-Seams, Air-Bubbles and Dirt-Bands, and Remarks upon Glacier Theories’, Phil. Trans., 149 (1859), pp. 279–307.
Lower Glacier of Grindelwald: a glacier in the Swiss Alps, below the Eiger.
laminæ: or laminae, a thin layer (OED), in this context referring to a layer in the ice.
stereoscopic plates: referring to stereoscopic photography.
Please cite as “Tyndall1612,” in Ɛpsilon: The John Tyndall Collection accessed on