cating beyond a question a distinct relation between the deviations in the force of gravity and the continental elevation. It will be seen that even where small changes only take place in proceeding from point to point they are, almost without exception, in the same direction in both curves. The proper interpretation of this fact is perhaps not easy. In the formula of Bouger, which is made use of in this reduction to the sea level, the only quantity that can be at all in doubt, or at least seriously in doubt, is the term involving the relative density of the surface matter to that of the earth itself, the other terms referring only to the decrement of gravity due to elevation. It might at first seem, therefore, that an adjustment of this term could be made which would harmonize the theoretical value of gravity and the observed values; that is to say, it might appear that it would be only necessary to alter our hypothesis in regard to the density of the surface matter of the earth in order to remove the discrepancies that are shown in the table and are exhibited so vividly in the diagram. When this is attempted, however, it is seen that no reasonable hypothesis with regard to the density of the continental mass of the earth will account for these differences. Indeed, to account for them would require the assumption that the density of the surface matter was not only not one-half of the mean density of the earth, but that it was not even so much as one-third of the mean density, or possibly not one-fourth, and in some cases, indeed, that it must be nothing at all, so that it is difficult to make the hypothesis accord with the facts.

It may be well to remark that the studies of the trans-continental system of triangulation, which is now nearly completed along the 39th parallel, seem to show that the figure represented by Clark's spheroid is in very close agreement with the reality as developed by this scheme, so that no large discrepancies in the value of the force of gravity can be expected to result from any possible error in the representation of the geoid by this figure.

These results are certainly of much interest and importance. to geologists, and it seems that they may, when the subject is sufficiently thoroughly investigated by further determinations widely and properly distributed, throw considerable light on the internal structure, and the formation of that part of the earth lying nearest the surface. They evidently demonstrate the great value and scientific interest of gravity determinations, conducted as skillfully and as rapidly as have been these under the direction of Mr. Putnam.

In connection with this subject, it may be of interest to add that during this campaign a number of comparisons were made of the half-second pendulum system, which was generally used

throughout the work, and the system of quarter-second pendulums for gravity purposes exhibited and described at a previous meeting of the Academy. These little pendulums, not more than five or six centimeters in length, have proved, under the test to which they were thus submitted, to be quite accurate and reliable in their performance, and their lightness and convenience in transportation will doubtless render them of considerable service in future gravity campaigns where the conditions of travel and observation are difficult and trying. It was also observed, by very careful comparisons of the periods of the pendulums of both types, both before and after the campaign made at the base station at Washington, that there was almost, if not quite, no sensible wearing of the agate knife edges, thus demonstrating the efficiency of the combination of plane and edge which was a year or two ago first presented to the National Academy.*

ART. VII. Observation upon the Glacial Phenomena of Newfoundland, Labrador and Southern Greenland; by G. FREDERICK WRIGHT.

Dr. F. A. Cook's expedition to the Arctic regions in the summer of 1894 met with many reverses, ending in the loss of the Steamer Miranda and of the valuable collections which had been made by the naturalists on board. But the opportunities for glacial investigation were on the whole as good as could have been reasonably expected. The delays afforded nearly a week for observations in Newfoundland, and about the same length of time at three different points in Labrador, namely at Henley Harbor, St. Charles Harbor, and the Punch Bowl, while two weeks were at our disposal in Greenland in the vicinity of Sukkertoppen in latitude 65.25, where the inland ice sends a projection down to within fifteen miles of the open sea. Besides spending a week in camp at the edge of this portion of the inland ice, we made an excursion up Isortoki Fiord to a distance of twenty-five miles, having oppor

Since the above was written I have received a letter from Mr. Putnam in which he informs me that he has since added two or three stations to the list as given above. He also makes the important suggestion that a similar line of gravity stations should be run across the southern part of the country. "We would then," he says. "get in another latitude a variety of conditions not found in the past season; a sea coast free from the mountains. along the Gulf Coasts an unmense area of deposits, farther to the west a long, rising swell comparatively little disturbed with mountains, and beyond a great depression below sea level." It is earnestly hoped that he may be allowed to execute this interesting piece of work.

tunity to study the phenomena along each side to that point, and to get extensive views of the inland ice and of the country bordering it.

The glacial phenomena of Newfoundland have been very carefully studied by Mr. Alexander Murray and fully recorded in his paper before the Royal Society of Canada in 1882, published in the Proceedings and Transactions of that year, Sec. iv, pp. 55–76. I have little to add to what he has written, except to set the facts in their connection with those observed in Labrador and Southern Greenland, so as to assist in forming certain general conclusions.

The west coast of Newfoundland presents a nearly straight face to the sea, running about N.N.E. and S.S.W. The southwestern portion of the western coast rises in Cape Arguille to a height of 1800 feet. The rounded or sloping escarpments usually face to the westward, as if the ice-movement from that direction had covered the whole island.

The southeast and east coast is deeply indented with numerous large bays which for the most part trend in lines nearly parallel with the western face of the island. Grand Pond, whose surface is 116 feet above tide, has a depth of more than 1000 feet, its bottom being 988 feet below sea-level. The evidences of former occupation by glacial ice are universal in the island; glacial striae being found not only in the valleys opening out into the Atlantic, but upon the highest headlands. In the vicinity of St. John's the direction of the scratches varies, according to Murray, from N. 64 E. to S. 76 E. upon the higher lands, which are from 300 to 600 feet above the sea. On the summit of Signal Hill, which is about as high a point as there is upon the peninsula of Avilon, the direction. of the scratches is S. 86 E. At Torbay, a few miles north, at 300 feet above tide, the scratches are S. 76 E. On the Great Belle Island in Conception Bay the direction is N. 38 E., or very nearly in line with the axis of the bay. At Topsail Head, however, which lies on the south side of the bay, just opposite the island, and 650 feet above tide, the scratches point, according to Murray, N. 43 W. It seems to me, however, a fair question, whether the direction of movement was not here S. 43 E., bringing it nearly in line with the scratches upon the rocks on the highlands between Topsail Head and St. John's.

So far as I could learn, the transported material in the vicinity of St. John's is local, the bowlders on Signal Hill being all traceable to outcrops a few miles west, where the land is very nearly upon a level with the summit of the headlands. Taken altogether, and in connection with the phenomena in Nova Scotia and Labrador, and with the soundings

of the surrounding sea, there seems every reason to accept the conclusion of Mr. Murray, that the glacial phenomena of Newfoundland belong to a general movement which filled the Gulf of St. Lawrence and extended some distance out upon the Atlantic plateau in this latitude. 1st. The glacial scratches which appear near the summits of the highlands are often at right angles to those appearing in the shallow valleys, indicating a movement, at the climax of the period, which was largely independent of local features. At St. John's there is a considerable accumulation of till upon the southeast side of the harbor up to about 200 feet; but there are very few indications of any vigorous movement of ice along the axis of the harbor. It was with difficulty that I found any indications of movement at all underneath this till. The whole appearance was that the harbor had been filled with nearly stagnant ice, having but a slight movement making very fine scratches in the direction of the axis of the upper part of the harbor, which was northeast, or about at right angles to the scratches upon Signal Hill, and to those near the summit of the hill upon the south side of the harbor.

2. The depth of Grand Pond (988 feet below sea-level) coincides with numerous other facts indicating a preglacial elevation. In Conception Bay the general depth of the water is from 100 to 140 fathoms; but the depth across the mouth is only 80 fathoms, indicating a bank which is most likely a terminal moraine. The mouth of Holyrood Bay is crossed by a similar bank, convex on the inside, and is covered by only thirteen fathoms of water, while it suddenly deepens on both sides to forty fathoms. As is well known, also (see especially a paper by Prof. J. W. Spencer, Geol. Soc. of Am., vol. i, p. 68), the shallow water surrounding Newfoundland, and extending to Nova Scotia, is intersected by a deep channel extending from the Saguenay River down the St. Lawrence and through the Gulf, south of Anticosti Island, to the margin of the plateau which suddenly breaks off into the profounder depths of the Atlantic Ocean, about 200 miles from the present land. margin. This channel is, throughout its entire length, more than 1200 feet in depth, reaching towards its mouth a depth of nearly 2000 feet. Throughout its entire length, also, it is pretty sharply bordered by a margin of shallow water less than 500 feet in depth.

3. Along the coast of Labrador the most instructive feature of the scenery is its subdued character, especially when contrasted with the west coast of Southern Greenland. From the Straits of Belle Isle to Hamilton Inlet the entire coast came within reach of our vision. Everywhere the land rises pretty rapidly to heights of from 1000 to 2000 feet. But though the rocks