3 ° 
Captain Kater's account of the 
the cone is turned very smooth and close to its base is curved 
so as to avoid the acute angle, which would have resulted 
from continuing the side of the cone to the bottom. By this 
also the advantage was gained of a greater substance for the 
insertion of the screws used for attaching the bottom of the 
gallon to the cone. 
As soldering was thought objectionable, the bottom was 
ground to the cone, and it was supposed that it would thus 
have been sufficiently secure ; but on letting the gallons 
remain filled for 24 hours, in some a slight leakage became 
perceptible. After many experiments, the best remedy for 
this appeared to be a very minute quantity of fresh grease, 
carefully applied to the bottom of the cone and then almost 
wholly wiped off ; after which the bottom was firmly screwed 
in its place. 
The following was the method pursued in adjusting the 
gallon : 
If the gallon contained a considerable quantity, as one or 
two hundred grains of water too little, its capacity was 
enlarged by turning away a small portion from the flat 
bottom. If on the contrary the gallon contained too much, 
the base of the cone was ground away ; and it must be evi- 
dent that a very small quantity taken from this part would 
occasion a considerable variation in the capacity, one thou- 
sandth of an inch making a difference of about 17 grains. 
Errors of smaller magnitude were removed either by grind- 
ing down the top of the mouth, or by enlarging the aperture 
by using a cylindrical plug of brass with emery. 
The interior of the measure being carefully wiped dry, 
it was placed in the scale together with one of the gallon 
