EXPERIMENT STATION REPORTS. 173 



lection on the diseases of ^Michigan, butli as to naLuio and distribution. 

 For comparison the standard European collect ious of fungi are badly 

 needed. 



Respectfully submitted, 



o. n. COONS, 



Research Assistant in Plant Pathology. 



THE PNEUMATIC CHISEL APPLIED TO TREE SURGERY, 

 CUTTING OUT CANKERS, AND PRUNING. 



DY G. II. COONS, RKSKARni ASSISTANT IX PLANT PATIIOI-OGV. 



In tree surgery, it is necessary to open cavities, cut off broken, 

 splintered stubs and clear away decayed wood down 1o a sound base. 

 In pruning, it is necessary, in order to' prevent the retardation of the 

 wound callus, to avoid stubs and to make all pruning Hush with the 

 main branch. IMuch of the work in cutting out cankers, requires a tool 

 such as a carpenter's gouge. These operations of tr(>e surgery require 

 much work and some jobs require hours of chipping with llie chisel 

 and mallet. 



It was thought worth while to attempt to devise a means of cutting 

 down the labor entailed in these operations, and the pneumatic hammer 

 driving a chisel was experimented with as a cutting tool. 



To the author's knowledge, no other tool to do similar work has been 

 devised. There is, however, a rotary cutter driven at high speed by a 

 gasoline engine or other power, which is being perfected by Dr. G. E. 

 Stone^ of the Massachusetts Experiment Station. This rotarj' cutter 

 may become a valuable adjunct for tree surgery since it makes the 

 cleaning of cavities easy. 



The pneumatic tool is an adaptation of the pneumatic hammer used 

 in riveting and chipping, and in it the chisel is held and advanced by 

 the numerous (twenty-eight hundred per minute) blows of the piston 

 which is driven by compressed air. 



In these experiments, the pneumatic hammers w^ere attached to fifty 

 foot lengths of heavy -Availed hose carried from a 66 gallon range boiler 

 which served as the reservoir for air. Air pressure of fifty pounds or 

 over was maintained. This pressure was given by a one and one-half 

 horse power gasoline engine working an air-cooled pump. The method 

 of assembling the trial outfit is shown in the accompanying cut. Fig. 2. 

 The tables accompanying this article will give, for the size of the ham- 

 mer used, the volume of air required by each and a consultation of the 

 catalog of any firm making air compressors will give the capacity of 

 the different sizes of pumps. 



The chisels used were specially made and were on the order of a car- 

 penter's gouge. One was fashioned from a rasp and was bent to a 

 crescent shape, while the other was hammered out from tool steel to 



'G. E. stone in Start, E. A., Stone, G. E., and Fernald, H. T., Mass. Exp. Sta. Bui. 125:6 3 pp., 



