181 



for discussion by any one who troubles to read the evidence l>y which 

 controversial opinions are formed. But to return, assuming the half 

 herring bone with lateral cuts half way round the tree, assuming the 

 cuts to be reopened nineteen times and one-eighth of an inch removed 

 an each of these occasions — taking the initial cut as being aboul half 

 an inch in width, there will finally result; a scar three inches wide. 

 For the purpose of illustration Ave may suppose the trees after tapping 

 are given a rest of six months and then again tapped, this time on the 

 opposite side of the trunks, after another six months they will be 

 again tapped on the original side, opening lateral cuts immediately 

 below the original ones, at the end of a further half year the similar 

 process will be applied to the opposite side of the tree. In this way, 

 if the original lateral cuts were at intervals of six inches the whole 

 of the area of the trunk suitable for tapping would be worked over 

 once in two years, by which time the first formed scars would be 

 completely healed. 



It is clear too that each tree would be in use. that is being tapped. 

 on two occasions of twenty days each during the year, that is to say 

 would be in milk on 40 days in the year. It therefore follows 

 that 3W total number of trees fit for tapping must be tapped on each 

 day. Making an allowance for days on which by reason of stress of 

 weather, festivals, or other circumstances no tapping is possible, this 

 fraction may be taken as equivalent to 12 per cent. 



This may of course be divided into two lots of 6 per cent, for 

 morning and evening tappings. 



Whether each individual tree be reopened on each successive day 

 or on alternate days will not affect these results, it would mean that 

 different sets of trees would be worked on alternate days but each set 

 would comprise 12 per cent, of the total trees. 



The division of the trees into groups for morning and evening 

 tapping will make it advisable to cut the central channel for the 

 morning group on the South side of the truk that for the evennig on 

 the north side of the tree so as to avoid the coagulation of the latex 

 in the cuts by the influence of sunshine. 



The preceding calculation can be put in general terms and a 

 formula given thus, 



Let W be the width of the first cut. 



— m be the thickness removed by each subsequent cut. 

 T be the interval of rest between successive tappings, 



measured in years. 



— t be the number of times each cut is reopened. 



— D be the days per annum when tapping is impossible. 



Then the spaces to be left between the lateral branches of the 



, . , tw + W 

 herring bone are m 



100 t + 100 



The percentage of trees tapped daily q«c rn _ jyv 



The thicknesses are measured vertically in inches. By stating 

 the matter in this condensed form the nature of the inconstant quan- 

 tities is clearly realised. 



