Page:Popular Science Monthly Volume 59.djvu/302

292 Such was the condition of observational meteorology in America at the time when Mr. A. Lawrence Rotch conceived the idea of establishing a meteorological observatory on the Great Blue Hill, near Boston. At first Mr. Rotch intended to use this observatory for special investigations, leaving the regular work to Signal Service observers. As no plan of cooperation with the Signal Service was found feasible, he determined to carry on the entire work under his own direction and at his own expense.

Mr. Rotch was particularly fortunate in his choice of a site for his observatory. Although the summit of the Great Blue Hill is but 635 feet above sea level, yet it possesses many of the characteristics of a mountain. It is the highest point of land in eastern Massachusetts, and offers an unobstructed view for many miles in all directions. This feature has been particularly valuable in prosecuting cloud studies.

The location is so near the coast that the characteristic water and land influences on the atmospheric conditions can be perceived. Moreover the summit of the hill is near that critical altitude at which the diurnal variation of the wind changes from the low level type to the high altitude type. We had meteorological records from the Signal Service stations on Mt. Washington (altitude about 0,000 feet) and on Pikes Peak (altitude about 14,000 feet), but we had none from the lower altitude at which the powerful local influence of the ground surface ceases to be overpoweringly effective. Thus this observatory fitted into a vacancy which it was desirable to fill. Nor is this all. The wonderful success attending the recent extension of the work of the observatory to the exploration of the upper air by means of-kites has been in no small part due to the perfect adaptation of this locality for carrying on such