344 Scientific Reviews. 



are to be viewed as belojaging to the ^me basin ; as also, all streams 

 flowing into a firth, {jleuve,) belong to the same great hydrogra- 

 phical basin. From these general winciples we can understand, 

 then, the relation of the Nairn and Findhorn rivers with the basin 

 ef the Ness ; and the connection of these three rivers, together 

 with the Lossie, Spey, Cullen, and Deveron, with the great basin 

 of the Moray Firth. The fine streams of the Don, the Bee, and 

 the Esk rivers, form an equally well characterized basin to the 

 east. 



The chain of the Grampians does not consist of a main geogra- 

 phical chain, preserving the same direction, and accompanied by 

 a number of parallel or longitudinal chains, but is composed of 

 chains which, parallel to one another, are nevertheless at angles 

 more or less inclined to the general geographical direction, or ex- 

 tent of the country of mountains. These chains again have their 

 transverse ridges supported by buttresses, {contreforts,) like a 

 rampart ; and from this simple arrangement, results a kind of inr 

 dependent grouping of each particular chain. 



Two of these mountain groups, the Monadhleadh and the Cairn- 

 gorm, domineer over the plains of Nairn, Moray, and Banflf, and 

 the upland districts of Aberdeenshire. It was on these mountains 

 that the deluge of rain which produced the flood of the 3d and 4th 

 of August 1829, principally fell. The heat during the months of 

 May, June, and July, of that year, was unusually great, and as 

 the season advanced, the learned author of the volume before us 

 observes, the fluctuations of the barometer became very remark- 

 able ; meaning, we suppose, that there occurred the irregular o*» 

 eillations which present phenomena directly opposite to the amount 

 of the diurnal or annual movements. These oscillations were not 

 followed by the usual alternations of weather. " The aurora bo- 

 realis appeared with uncommon brilliancy about the beginning of 

 July, and was frequently seen afterwards, being generally accom- 

 panied by windy and unsteady weather, the continued drought 

 having been already interrupted during the previous month by 

 sudden falls of rain, partaking of the character of water-spouts." 

 (Some remarkable instances of these water-spouts are mentioned.) 

 The rivers Nairn, Findhorn, and Lossie, were all more or less zi- 

 fected by the flood, exactly in proportion as they were more or less 

 connected with the mountain in question. The mouth of the lat- 

 ter river was perhaps the most important scene of action. 



The Spey from below Kingussie, and its tributaries, were ele- 

 vated to an unexampled height ; and the Deveron, the Don, the 

 Dee, and the two Esks, were each of them operated upon in a si- 

 milar degree. Mr. Murdoch, gardener to his grace the Duke of 

 Gordon at Huntly Ledge, informed the author that 3f inches of 

 rain fell between 5 A.M. of the 3d, and 5 A.M. of the 4th of Au- 

 gust, •v^hich appears to be, taking the average of the years from 1821 

 to 1828 inclusive, about one-sixth part of the usual annual fall. 



