\ 



190 MISSOURI BOTANICAL GARDEN 



standing 



the roots in two. These 



mini 



and were rather carelessly placed in position. The top cross 

 pieces w r ere simple flat pieces of planking which were 



dged 



The rotting usually oc- 



curred in the oak supports. Because the weight sustained 

 is not excessive the timbers rot practically throughout their 

 diameter and for a considerable distance in length before, 

 they must be replaced. The clay mines are worked for a 

 number of years, and the timbers must be renewed several 

 times, as they last only about two to three years ordinarily. 

 The timbers used were oaks of various species, and southern 

 pine. The oak pieces were used as braces at the sides, while the 

 cross pieces overhead w T ere of pine. The oak pieces were 



from 



bark removed, while the pine pieces were sawn mostly from 

 heartwood, and were usually 2 to 3 inches in thickness, and 

 about a foot in width. The pine was used for the overhead 

 timbering because of its greater resistance to rot, it 



being 



of the timb 



untreated 



in the proper sizes and shapes for use. It is shipped 



somew 



time it is placed in the mine, although little or no attention 



to 



fungi growing upon the timbers in these mines 



was 



situated under very abnormal conditions. There 

 lutely no light, and the air of the mines was noticeably 

 moister than that out of doors. The temperature never 

 goes down to freezing, and is very uniform, ordinarily being 

 cool enough so that one may wear a coat with comfort even in 

 the hottest weather. In most of the galleries the sides and top 

 were fairly moist, but not dripping, while in others the 

 moisture was very noticeable, there even being small rivu- 

 lets of water running along the tramway to the lowest parte 

 of the mine. In all cases the water seeping into the mine 

 had to be pumped out to prevent its filling the galleries. 



