No. 4.] WEATHER AND ITS INFLUENCE, 51 



rate of movement of the low and high, with the blowing of the 

 wind from the high toward the low, coming weather changes may 

 be foreseen by a glance at the map. The centres of low do not, 

 as a rule, move across isotherms, but follow their general direc- 

 tion. Areas of low pressure frequently move to the soutli of east 

 from the Rocky Mountains to the Mississippi, and then change 

 direction to the north of east over the eastern half of the country. 

 Storms in the Gulf of Mexico occasionally move to the west or 

 north of west, but after reaching the coast they generally change 

 direction and move to the north-eastward. High areas move to 

 the south-east, and ai'e attended by fair and cold weather. A cold 

 wave is always accompanied by a high. 



The cloud and rain area in front of a low is generally about the 

 size of the latter, and oval, with the west side touching the centre 

 of the low in advance of which it progresses. 



AVhen the isotherms run nearly east and west no decided change 

 in temperature will occur. If the isotherms directly Avest of a 

 place incline from north-west to south-east, it will be warmer ; if 

 from north-east to south-west, it will be colder. Southerly winds 

 prevail west of a nearly north and south line cutting the middle of 

 a high, also east of a like line cutting the middle of a low. 

 Northerly winds occur west of a nearly north and south line pass- 

 ing through the middle of a low and also east of a similar one 

 thi'ough the middle of a high. 



An absence of decided waves of high or troughs of low pres- 

 sure indicates a continuance of existing weather which will last 

 till later maps show a change, usually first appearing in the west. 



The sensible temperature published in the table with the map 

 is the reading of the wet thermometer (a thermometer the bulb of 

 which is always kept moistened), and represents the temperature 

 which is felt at the surface of the body, especially Avhere the skin 

 is exposed, as on the face and hands. When the air is dry, this 

 temperature, owing to the rapid evaporation of moisture, is con- 

 siderably lower than the actual temperature of the air. 



Evening Session. 



The evening lecture was given by Hon. "William E. 

 SiMONDS of Hartford, Conn. The subject was "Man the 

 creator; the development of inventions." The lecture was 

 listened to with rapt attention by a large and appreciative 

 audience, and was exceedingly instructive and entertaining. 

 It was beautifully illustrated by the stereopticon. By agree- 

 ment the lecture is withheld from publication. 



