THE FLOW OF MAPLE SAP 



BY A. H. WOOD. 



Note. — Professor Wood resigned his position on tlie Station Staff 

 November i, 1S94. 



This bulletin is chiefly based upon observations made while 

 engaged in procuring samples of maple sap for investigation as 

 recorded in Bulletin No. 25. 



These results are submitted at this time, not as a complete 

 study of the subject, but because the results recorded may be 

 of immediate value to the sugar makers of the state. 



It has become a common practice to tap maples to a depth of 

 only about an inch. This practice is based upon the belief that 

 the flow of sap comes chiefly from the wood of very recent 

 growth, and that to tap beyond the growth of the last six or 

 eight years is a useless expenditure of labor and an unnecessary 

 injury to the tree. 



To determine as to the correctness of this belief, as well as 

 to investigate the comparative richness of the sap from the 

 outer and inner wood, the following experiments were made. 

 In the spring of 1892, two thrifty rock maples about fourteen 

 inches in diameter and growing in thick woodland were selected 

 and tapped as shown in Table i. 



TABLE 1.— RELATION OF DEPTH OF TAPPING TO FLOW^ OF SAP. 



1892. 



Tree A. 



1% inches 



deep 



(south). 



March 25 



" 26 



" 28 



" 30, 



April 1, 



4, 



10, 



12, 



" 16. 



5.0 lbs. 



3.5 " 



4.0 " 



7.5 " 



8.0 " 



2.0 " 



11.0 '■ 



8.5 " 



4.0 " 



53.5 lbs. 



3i;2 inches 



deep 



(north). 



8.0 lbs. 



3.0 " 



6.0 " 



14.0 " 



16.0 " 



5.0 " 



19.0 " 



18.0 " 



16.0 " 



105.5 lbs. 



Tree B. 



1% inches 



deep 



(north). 



31/2 inches 



deep 



(south). 



7.0 lbs. 



1.5 " 



1.5 " 



2.0 " 



2.0 " 



1.0 " 



8.0 " 



8.0 " 



5.0 " 



8.0 lbs 



3.5 



3.0 



6.0 



6.0 



3.0 

 17.0 

 20.0 

 15.0 



36.0 lbs. 



81.5 lbs. 



