tapped on each day. Making an allowance lor 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%. 
This may of" course be divided into two lots of 6 % for morning 
and evening tappings, 
Whether each individual tree be reopened on each successive day 
or on alternate davs will not affect these results, it would mean 
that different sets of trees would be worked on alternate days but 
each set would comprise 13% 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 trunk, that for the ev ening 
tapping 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. 
. w 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 jji 
100 1 + 100 
The percentage of trees tapped daily ggfpr _ jyrp - 
The thicknesses are measured vertically in inches. By stating 
the matter in this condensed form the nature of the inconstan 
quantities is clearly realised. 
Thus W the width of The first cut depends upon the tool used 
and the skill of the user, similarly for the value of zv. If for in- 
stance w could be made 1/16 instead of i/8 inch it would reduce 
the space between the side arms of the herring bone from 6 inches 
to 3- 1 . assuming the value for t to be constant. Whether this would 
he too dose for practical work, whether the areas drained by the 
separate cuts would seriously overlap is not known, on this point 
experiments are needed, because it is certain that before long a 
special tool to cut a thin shaving not more than j/i 6 inch will be 
available. 
Then the value of /, the times of reopening, is at present not 
fixed. Various values ranging from io to 25 have been assigned 
as suitable. Experimental results are here needed, and probably 
each estate will eventually have a special value for this quantity. 
For the moment it can be safely assumed that 15 is not too high 
a value. 
