496 TRANS. ST. LOUIS ACAD. SCIENCE. 



The mean and. extreme daily Temperatures in St. 

 Louis during forty seven years, as calculated from 

 daily observations, 



By Dr. George Engelmann. 



Half a century has passed since I began to study the meteor- 

 ology and climatology of this neighborhood, and since the year 

 1S36 I have made regular meteorological observations, first on 

 temperature, the winds and the condition of the sky, and soon 

 afterwards on atmospheric pressure, rainfall and humidity. 



I give here the results of my thermometrical observations, 

 which I consider as the most important and most interesting of 

 the series. They comprise, to be sure, only forty-seven years, and 

 I might have waited until at least half a century was completed ; 

 but the results would scarcely have been different, and the task 

 then perhaps problematical of accomplishment. 



The observations were made within the city of St. Louis, and 

 can thus not claim precision for this whole region. St. Louis, 

 to be sure, was, when they commenced, a small town of perhaps 

 15,000 inhabitants, while now, at their completion, it is a large 

 city of probably 400,000, with the necessary accompaniment of 

 brick and stone, and especially with the smoke of thousands of 

 chimneys, furnaces and factories, and the almost total absence of 

 verdure. It has been held by some, that these influences had 

 little effect on temperature, but that brisk breezes would soon dis- 

 pel smoke and equalize temperature. This, however, is not quite 

 so, and direct thermometrical comparisons prove that the extreme 

 temperatures, and, remarkably enough, even the extreme heat, 

 are less marked in the city than in the country, and that the mean 

 temperature is higher in the city than in the country (Trans., 

 vol. ii., p. 70) ; but, aside from instrumental observation, the 

 state of the vegetation proves it every spring and fall, when we 

 find in our city gardens the plants uninjured on mornings when 

 in the country they have suffered from late or early frosts. 



St. Louis lies very nearly in the centre of the Mississippi Valley, 

 600 miles north of the Gulf of Mexico and just as far south of Lake 

 Superior, about 500 miles west of the Alleghanies and 800 miles 

 east of the Rocky Mountains ; its Washington University, one 



