TIREY. GENERAL DESCRIPTION. . 25 



doubtless one of the leading causes of the general 

 fertility of the soil, and of the little injury which re- 

 sults from the sand drift, the effects of which in many 

 of the Western Islands are so conspicuous, and often so 

 injurious. In consequence of its level and unobstructed 

 surface, the sand is distributed by the winds over the 

 flat parts of the island in so equable a manner as to im- 

 prove the whole by the perpetual renewal of a calcareous 

 manure ; while it scarcely any where accumulates to such 

 a degree as to suffocate or repel vegetation. The differ- 

 ences in this respect are very apparent, where the rocky 

 surface, affording local shelter, causes the sand to accu- 

 mulate, as on the northern end of this island and through- 

 out the whole of Coll; and they will receive further 

 illustration hereafter, when the state of the sandy accu- 

 mulations on the western shores of the Long Island are 

 described. I may add, that the moisture of Tirey, arising 

 from the causes formerly stated, affords a powerful pro- 

 tection against the blowing away of the soil ; by maintaining 

 a perpetual coat of vegetation on the surface, which 

 prevents the wind from acting on it. From these circum- 

 stances, the cultivated land of the island is perhaps in 

 many cases less profitable than it would be in pasturage, 

 were it possible to calculate its value on any other 

 agricultural system than that which the extreme population 

 of this island, as of many other parts of the Highlands, 

 renders necessary, or rather indispensable. In consequence 

 of this state of the soil, cross ploughing is rarely used, 

 but the seed being sown on the first furrows, is 

 harrowed in by a light harrow, so that in springing it 

 assumes the appearance of a drilled crop in eveiy respect 

 but cleanness; since the intermediate sod is generally 

 occupied by an equal line of weeds. Under even this 

 miserable proceeding, good crops of barley, oats, potatoes, 

 and flax are produced ; sown grass and turnips having 

 here, as in most of the islands, scarcely yet found their 

 way into the agricultural system. The chief manure in 

 use, is that of drift fuci. 



