74 Proceedings of the Royal Irish Academy. 



that described by M'Adam, and shown by bim to be of common 

 occurrence on several of the countries of northern Europe. 



Moreover, it is to be noted that he speaks of those mills being 

 prevalent over all Greece, and to be found in Asia Minor ; lastly, they 

 are in Greece, at least in the example described by him, more carefully 

 constructed and more skilfully disposed than in those northern 

 examples already described. Unfortunately, as to the origin of the 

 mechanism or the historical side of the question, there is nothing but 

 what may be interpreted from the epigram of Antipater ; and although 

 the wording of this would allow of its being understood to refer to a 

 water-mill with Aor/zoJi^a/ buckets, such as described by Castellan, the 

 terms employed are not sufficiently clear, nor sufficiently technical, to 

 prevent them being equally applicable to a mill-wheel with hori%ontal 

 axis and huclcets, such as are usually employed at present in these 

 countries. Two further points are also worth calling attention to : 

 1st, that occuning in the citation from the Montgomery MSS., p. 321^ 

 given by M'Adam, where it is said: "the water-wheel lo as fixed at 

 ye lower end of ye axle-tree, and did run horizontally amony ye water, a 

 small force driviny it.'''' This most important remark proves that the 

 former users of this form of water-mill had ascertained by experience 

 the advantage it presents in being able to work when drowned, that is 

 when completely covered by water. iN'ow this is precisely one of the 

 advantages claimed for the most modem and most perfect forms of 

 turbine, working as they do with remarkably small heads of water. 

 2ndly, in the citation from Lockhart's "Life of Sir Walter Scott," 

 describing his tour in the Shetland Islands, he describes the conditions 

 affecting the rude mill he meets with at Loch Cleik-him-in. "It is 

 divided," he says, "by a rude causeway from another small lough,, 

 communicating with it, however, by a sluice for the purpose of driving 

 a mill ; but such a mill ! " Now it is evident that the upper lake was 

 taken advantage of to retain or pond a head of water, while the lower 

 lake, being allowed to find its own level, gave thus rise to a difference 

 of level or head of water utilized for driving the mill, the sluice 

 being established to allow the overflow of floods or high waters. It 

 is evident, therefore, that the ancient users of these mills knew how 

 to create the necessary head of water, simply by cutting off a part of 

 a lake or other surface of water by a dam or wall, taking care to 

 insert a sluice to meet the requirements of the necessary occasiona 

 overflow. But this simple device, so easily understood in the case of 

 a lough, is equally applicable in the case of small tidal estuaries or 

 inlets, such as occur with great frequency on the northern or Canta- 



