30 Hon. Ralph Abercroinby on the peculiar 



read before the Physical Society of London, May 27, 1876, 

 and published in the Philosophical Magazine for July 1876. 

 Writing from descriptions, for he himself had never witnessed 

 the appearance, Mr. Abbay says: — At sunrise apparently an 

 enormous elongated shadow of the mountain is projected to the 

 westward, not only over the land but over the sea, to a dis- 

 tance of 70 or 80 miles. As the sun rises higher, the shadow 

 rapidly approaches the mountain, and appears at the same 

 time to rise before the spectator in the form of a gigantic 

 pyramid. Distant objects — a hill or a river (or even Colombo 

 itself, at a distance of 45 miles) — may be distinctly seen 

 through it ; so that the shadow is not really a shadow on the 

 land, but a veil of darkness suspended between the observer 

 and the low country. All this time it is rapidly rising and 

 approaching, and each instant becoming more distinct, until 

 suddenly it seems to fall back on the spectator, like a ladder 

 that has been reared beyond the vertical ; and the next instant 

 the appearance is gone. For this the following explanation 

 is proposed : — The average temperature at night in the low 

 country during the dry season is between 70° and 80° F., whilst 

 that on the summit of the Peak is from 30° to 40°. Conse- 

 quently the lower strata of air are much less dense than the 

 upper ; and an almost horizontal ray of light passing over 

 the summit must of necessity be refracted upwards and suffer 

 total internal reflection as in the case of an ordinary mirage. 



It will be remarked that Mr. Abbay does not allow for the 

 difference of elevation, and the sequel will show that this 

 theory cannot be maintained. 



Adam's Peak is a mountain that rises in an abrupt cone, 

 more than 1000 feet above the irregular chain to which it 

 belongs; the summit reaches to 7352 feet above the sea. 

 On the south side the mountain falls suddenly down to 

 Ratnapura, very little above the sea-level ; while on the 

 north it slopes irregularly to the high valley of the Maskeliya 

 district. The peak also lies near an elbow in the main chain 

 of mountains, as shown in the diagram of the topography of 

 the Peak (fig. 1), while a gorge runs up from the north-east 

 just to the west of the mountain. When, then, the north- 

 east monsoon blows morning mist up the valley, light wreaths 

 of condensed vapour will pass to the west of the Peak and 

 catch the shadow at sunrise only, if other things are suitable. 

 The importance of this will appear later on. 



The only difficulty in getting to Adam's Peak is the want 

 of a rest-house within reasonable distance of the summit. 

 Fortunately the kindness and hospitality of T. N. Christie, 

 Esq., of St. Andrew's Plantation, Maskeliya, enabled the 



