22 PROCEEDINGS OF THE AMERICAN ACADEMY 



morning north of Lake Superior, and moved to western Canada in 

 the course of the next twenty-four hours. During the afternoon of 

 this hot day (mean max. 82°), several rather strong storms occurred in 

 northeastern Massachusetts, and scattered reports came from farther 

 north and west. Showers without thunder are also reported. The 

 two storms that can be partly defined began in northeastern Massachu- 

 setts ; the first about noon, the second a little farther west than the 

 first, at IS*" to 14^ Both moved east-northeast at about 20 miles an 

 hour, and passed out to sea over Cape Ann and farther north. On 

 account of their coming so close together, it is difficult to distinguish 

 them in some of the reports, but they showed the usual control over 

 the winds and temperature at a number of stations. At a moderate 

 distance away, the wind blew with moderate or light velocity towards 

 the storm ; nearer the rain area, and especially at times of heavy rain, 

 the wind blew away from it, and for a time with increased strength. 

 North of Salem, where the rain was especially heavy, the wind blew 

 outward even at the back of the storm ; this seldom appears, and in 

 this case seems to be connected with the low velocity of the storm, and 

 with its lateral or backward growth to the westward, even while mov- 

 ing east. The storms as a whole were seen from Cohasset, south of 

 the Bay, moving slowly in an easterly direction ; their angular altitude 

 was estimated to be 20° ; their distance must have been at least 20 

 miles, and was more likely 22 miles. This would make their height 

 six or more miles. 



An appreciative record from Southampton, Mass., on this date, 

 describes in detail the extension of the rain area in a local thunder- 

 shower in a direction contrary to the movement of the clouds, as above 

 suggested. Cumulus clouds of ordinary type had been seen growing 

 to larger and larger size from 10'\30, and moving from the southwest 

 while the surface breeze blew towards them from the southeast. 

 About noon, rain was seen falling from the clouds, and thunder was 

 heard a little later. Then additional cumuli, cominff from the south- 

 west, developed very rapidly as they approached the shower, build- 

 ing the thunder-cloud southward. " The shower as a whole had a 

 movement to the northeast, but the development of the cloud area in 

 the manner noticed exceeded the velocity of the shower movement." 

 Other observers describe this shower as moving slowly ; it would be 

 an excellent one for study had our stations been more numerous in 

 this district. Its motion and that of several neighboring showers was 

 from west to east, or a little to north of east, and the velocity seems 

 to have been moderate, although this is poorly defined by our records. 



