Portions of New England present the best illustrations anywhere afforded in America of what are called "drumlins." These are "lenticular-shaped" hills, composed of till, and containing, interspersed through their mass, numerous scratched stones of all sizes. They vary in length from a few hundred feet to a mile, and are usually from half to two-thirds as wide as they are long. In height they vary from twenty-five to two hundred feet. But, according to the description of Mr. Upham, whatever may be their size and height, they are singularly alike in outline and form, usually having steep sides, with gently sloping, rounded tops, and presenting a very smooth and regular contour. From this resemblance in shape to an elliptical convex lens, Professor Hitchcock has called them lenticular hills to distinguish these deposits of till from the broadly flattened or undulating sheets which are common throughout New England. [Illustration: Fig. 27.--Drumlins in Goffstown, N. H. (Hitchcock).] The trend, or direction of the longer axis, of these lenticular hills is nearly the same for all of them comprised within any limited area, and is approximately like the course of the striæ or glacial furrows marked upon the neighbouring ledges. In eastern Massachusetts and New Hampshire, within twenty-five miles of the coast, it is quite uniformly to the southeast, or east-southeast. Farther inland, in both of these States, it is generally from north to south, or a few degrees east of south; while in the valley of the Connecticut River it is frequently a little to the west of south. In New Hampshire, besides its accumulation in these hills, the till is frequently amassed in slopes of similar lenticular form. These have their position almost invariably upon either the south or north side of the ledgy hills against which they rest, showing a considerable deflection towards the southeast and northwest in the east part of the State. It cannot be doubted that the trend of the lenticular hills, and the direction taken by these slopes, have been determined by the glacial current, which produced the striæ with which they are parallel.[AY] [Footnote AY: Proceedings of the Boston Society of Natural History, vol. xx, pp. 224, 225.] Drumlins are abundant in the vicinity of Boston, and constitute nearly all the islands in Boston Harbour. On the mainland, Beacon Hill, Bunker Hill, Green Hill, Powderhorn Hill, Tufts College Hill, Winter Hill, Mount Ida, Corey Hill, Parker Hill, Wollaston Heights, Prospect Hill, and Telegraph Hill are specimens.