156 FRAGMENTS OF SCIENCE. 



" In the face of these hills," says this writer, " both sich j s 

 of the glen, there are three roads at small distances from 

 each other and directly opposite on each side. These 

 roads have been measured in the complete parts of them, 

 and found to be 26 paces of a man 5 feet 10 inches high. 

 The two highest, are pretty near each other, about 50 

 yards, and the lowest double that distance from the near- 

 est to it. They are carried along the sides of the glen with 

 the utmost regularity, nearly as exact as drawn with a lino 

 of rule and compass." 



The correct heights of the three roads of Glen Roy are 

 respectively 1,150, 1,070, and 860 feet above the sea. 

 Hence a vertical distance of 80 feet separates the two high- 

 est, while the lowest road is 210 feet below the middle 

 one. 



These '" roads'' are usually shelves or terraces formed in 

 the yielding drift which here covers the slopes of the 

 mountains. They are all sensibly horizontal and therefore 

 parallel. Pennant accepted as reasonable the explanation 

 of them given by the country people in his time. They 

 thought that the roads tf were designed for the chase, and 

 that the terraces were made after the spots were cleared in 

 lines from wood, in order to tempt the animals into the 

 open paths after they were roused, in order that they might 

 come within reach of the bowmen who might conceal them- 

 selves in the woods above and below/' 



In these attempts of " the country people" we have an 

 illustration of that impulse to which all scientific knowl- 

 edge is due the desire to know the causes of things; and 

 it is a matter of surprise that in the case of the parallel 

 roads, with their weird appearance challenging inquiry, 

 this impulse did not make itself more rapidly and energet- 

 ically felt. Their remoteness may perhaps account for 

 the fact that until the year 1817 no systematic description 

 of them, and no scientific attempt at an explanation of 

 them, appeared. In that year Dr. MacCulloch, who was 

 then president of the Geological Society, presented to that 

 Society a memoir, in which the roads were discussed, and 

 pronounced to be the margins of lakes once embosomed in 

 Glen Roy. Why there should be three roads, or why the 

 lakes should stand at these particular levels, was left unex- 

 plained. 



To Dr. MacCulloch succeeded a man, possibly not so 



