292 PROCEEDINGS OF THE ACADEMY OP 



ments from ancient Indian mounds, without ever seeing any made of the pipe- 

 stone. Acting on this suggestion, Dr. H. examined such works as were within 

 his reach, and he could not ascertain that the numerous and careful explora- 

 tions of the mounds in the Mississippi Valley have as yet revealed any ornaments 

 made from this rock. The Indians must therefore have discovered the quarry 

 since the stone age. 



Dr. H. exhibited a number of ornaments manufactured from the Pipestone 

 by the North-west Fur Company. They consist of pipes of various patterns 

 and sizes, cups, candlesticks, etc. They are turned in a lathe. Within a year 

 or two this company have made nearly two thousand pipes, which they send 

 up to the Upper Missouri Indians, near the foot of the Rocky Mountains, and 

 trade them for a robe a-piece. Hereafter some doubt will be thrown upon the 

 genuineness of these Indian pipes. 



On favorable report of the Committee the following were ordered to 

 be published. 



On the Period and Ratio of the Annual Increase in the Circumference of Trees. 



BY THOMAS MEEHAN. 



The following experiments were instituted in order to ascertain whether the 

 production of wood in trees was more rapid during some portions of the grow- 

 ing .season than others, and at what periods growth commenced and ceased in 

 the species of tree chosen. 



The Carolina poplar (Populus monilifera Ait.) was selected on account of 

 its rapid growth, enabling me to easily note the increase of circumference 

 each seven days. 



The following table shows the result. For the sake of system, the same day 

 in the week was chosen. In order to tabulate the figures, the same date is 

 used for the three years ; but as the same day fell on different dates, there is a 

 difference of three days in each date. For instance, May 17 in 1863 is May 18 

 in 1862 and May 20 in 1866 the three years during which the measurements 

 were taken. 



