April 18, 1913] 



SCIENCE 



611 



face is worked out for Iceland spar. Here it 

 is shown how a ray may fall obliquely upon a 

 plane surface without suffering refraction. 

 Here too is set forth the invention of the el- 

 lipsoidal wave surface to explain refraction in 

 uniaxial crystals — one of the cleverest chap- 

 ters in the entire history of science. The 

 sixth chapter is given over to " the figures of 

 transparent bodies which serve for refraction 

 and for reflection." Here the principle of 

 " equivalent optical paths " is employed with 

 its well-known elegance. The thanks of all 

 students of optics are due to both translator 

 and publisher for this complete and accurate 

 rendition of a memoir which has long been so 

 rare and expensive as to be practically out of 

 reach of the ordinary reader. 



H. 0. 



SPECIAL ASTICLES 



THE HISTORY OF LOST RIVER 



In a previous paper written over a year ago 

 and published by the Society for Protection of 

 New Hampshire Forests, in their annual re- 

 port for 1911, I tried to solve the problem 

 which Lost River presents. Since that time 

 I have made several visits to Kinsman Notch 

 and have each time found new evidence on 

 which to base conclusions. The following 

 paper is offered as a further attempt at an ex- 

 planation, based on the new evidence. 



Lost River is a small stream rising in Kins- 

 man Notch, about seven miles in a westerly 

 direction from North Woodstock, New Hamp- 

 shire. 



The spectacle which presents itself on enter- 

 ing the river is very confusing. The river is 

 immediately lost to view among a mass of 

 huge granite blocks, some of them as large as 

 average dwelling houses. Large potholes are 

 numerous, as well as many beautifully curved 

 water channels. Many of the potholes are 

 fractured and fragments of these lie in the 

 general mass. By careful inspection it is seen 

 that this is an old rock gorge, and that some- 

 thing violent has taken place. Many joint 

 blocks have fallen in, making it impossible to 

 follow the water of the river in its course 

 without ladders and bridges. The Society for 



Protection ©f New Hampshire Forests, has 

 purchased 148 acres, including the Lost 

 River and the overhanging cliff, and has 

 placed ladders and bridges in the gorge, so it 

 is no longer difficult to see all the interesting 

 points. There are two sets of caverns (so 

 called because of large vacant spaces between 

 the joint blocks), an upper and a lower. The 

 upper caverns are about one quarter of a mile 

 long. The stream emerges from these at Para- 

 dise Falls, flows unobstructed for about 150 

 feet, and plunges again beneath another mass 

 of joint blocks, the lower caverns. The latter 

 are not so imposing nor as extensive, although 

 very interesting. 



In contemplating this heap of granite blocks 

 with the purpose of finding an explanation to 

 the riddle, there are three agents which pre- 

 sent themselves as seemingly capable of bring- 

 ing about such confusion : frost action on a 

 large scale ; the disruptive force of a moving 

 glacier; and earthquake action. 



There has been considerable frost action in 

 the gorge, and without doubt many blocks 

 have been slowly wedged apart and fallen 

 down from the sides of the gorge. That frost 

 action, however, does not account for all the 

 falling and movement, is to me quite evident. 

 When in the lowest caverns one finds cases 

 where blocks which have slipped from between 

 other huge blocks in place, have left the upper 

 and lower blocks entirely unmoved in the solid 

 ledge. Smooth slickenside-like patches give 

 evidence of a rapid and violent movement. 

 This does not resemble frost action. The 

 fearful confusion and pell-mell attitude of the 

 mass also bespeak something more than the 

 gradual work of frost. 



The disruptive force of a moving glacier 

 would seem at first glance capable of creating 

 such a confused mass of joint blocks. It could 

 not account, however, for the movements be- 

 low the solid ledge, as described above. In one 

 case I found a movement in a lateral direction 

 between two blocks. The lower one is evi- 

 dently in place and a part of the solid ledge, 

 and the upper one has moved against the di- 

 rection of movement of the ice about four 

 inches. If ice were accountable for the slip, 



