cclxiii 



"June 4, 1877. 



Dr. Geo. Engelmann in the chair. 



Twelve members present. 



Dr. Geo. Engelmann made the following communication on 

 the Meteorology of the past spring, remarking that differences 

 between his observations and those made either in the heart of 

 the city, or farther out into the country, are readily explained by 

 radiation from buildings and pavements, and the prevention of 

 terrestrial radiation by smoke-clouds. 



The temperature of the spring months, March, April and May, was low, 

 and in consequence of the development of the spring vegetation late, as 

 we all know. We may recollect that the spring of last year was earlier, 

 and especially the month of May much warmer; we then at once come to 

 the conclusion that this present was the coldest and latest spring. But 

 meteorological records will teach us differently; they also inform us that 

 it was not the wettest spring, nor the wettest May, on record. 



The average temperature for May in St. Louis is 66.2 deg. ; that of this 

 year was 63.5. The coolest May I have observed was in 1S3S, also in 1S67, 

 with 60.5 deg. ; and the warmest, in 1S60, with 72 deg. Three times in 42 

 years May was cooler than this year (in 1838, '57? '67) and three times of 

 the same temperature. It will be noted that these low temperatures in 

 May have come almost every ten years; for 1847 the temperature was the 

 same as this year. I have tried to ascertain whether this seeming peri- 

 odicity holds good for the whole spring, or the whole year, or for other 

 months of the year, especially for October, which is considered as con- 

 forming pretty nearly to the mean temperature of the year; but I have 

 failed to confirm such a supposition. 



The temperature of March was 5.8 deg. below the average for the 

 month, that of April 2.0, and of May, as has been stated, 2.7 below; the 

 whole spring, consequently, was 3.5 deg. below the average; and I find 

 only five springs in 42 years cooler than the past one (those of 1837, '43' 

 '57, '67 and '75). But the mean temperatures are not so important to us 

 as the extremes are; under the extremes we suffer most, we ourselves indi- 

 vidually as well as through their action on vegetable life and development. 

 March was wintry almost throughout, but in April we had only a few 

 days, in the beginning of the month, of hard frost; at the same time the 

 temperature rarely rose over 70 ; only once, on the 23d, it rose over So : 

 but on the last day a frost, light in the city, but severe in many localities 

 in the neighborhood, did some damage to the vegetation. In May the 

 temperature was also moderate, often scarcely warm enough for the sea- 

 son, and with me only rose up to 86°, while in the city it reached 90 . 



The past month of May appeared a very wet one, not only to us inhab- 

 itants of the city, but perhaps still more so to those that live in the coun- 

 try. The fall of rain, however, was not so very heavy, scarcely more than 



