TRANSACTIONS OF THE SECTIONS. 145 
. 
_ measures more complex and multiform. It ought therefore to be avoided, unless 
_ some necessity can be shown in its favour. Hence it would seem to be expedient to 
abolish from these calculations all primes except 2, 3, and 5 ; aud here an important 
question arises, viz. should these be retained, or shall we be satisfied with 2 and 5, 
omitting 3? 
We are thus brought to one of the great discussions of the present day, the expe- 
diency of decimalizing our measures, weights and coins. 
__ The consequence of the simple fact, 2x 5=10, is, that all decimal systems are also 
binary and quinary, the principal quantities expressed by tens, hundreds, thousands, 
&c. being divisible by 2 and by 5 without remainder, so that their doubles and their 
halves can be introduced and reckoned without the least difficulty or inconvenience. 
But such systems do not readily admit the number 3, because in the majority of cases 
the quantity cannot be divided by 3 without a remainder, and in many cases the 
division by 3 produces a repeating decimal]. This is the ground on which many 
persons have insisted on 12 as a multiplier for measures, weights, and coins, rather 
than 10. But it is to be observed, that if 10 cannot be divided by 8, on the other 
hand 12 cannot be divided by 5 without remainder. Hence it seems to follow, that 
the choice must be made between decimal and duodecimal modes of computation, 
according as a preference is given to 3 or to 5 as a divisor. If it is more necessary 
or convenient to divide by 3 than by 5, duodecimal methods are entitled to the pre- 
_ ference, so far as this circumstance is concerned. I cannot, however, discover any 
reason for making this assumption. I think it probable, that division by 5 is required 
_ as frequently as by 3, whilst every other consideration is decidedly in favour of the 
decimal scale. 
The investigation which we have been pursuing is, therefore, first, in favour of de- 
cimal measures, weights, and coins; and secondly, supports the views of those who 
_ think that the subordinate multiples and divisions should be made by 2 and 5 only, 
and not by 8. 
___ In this conclusion I have the satisfaction to observe that I am countenanced by 
the authority of the late Mr. Drinkwater Bethune, one of the Commissioners appointed 
_by the present Lord Monteagle, when Chancellor of the Exchequer, to consider the 
_ steps to be taken for restoring the standards of weight and measure. In his letter to 
the Chancellor of the Exchequer, dated 21st of September, 1841, he maintains the 
following positions :— 
Ist. That “the Tables of Weights and Measures now in use are complex and in- 
convenient, and that it is very desirable to get rid of inconvenient multiples such as 
the factor 7, which connects the pound avoirdupois with the stone, and thereby with 
its multiples, the hundredweight and ton; and the factor 11, which connects the yard 
with the chain, and thereby with the mile and acre.” 
- 2nd. That ‘it is desirable, that no numbers, which are not multiples either of 2 or 
of 5, should anywhere appear in the Tables.” 
MECHANICAL SCIENCE. 
Big. Address by Loryv Rosse, the PresipEnt of the Section. 
ORD Rosse commenced by apologizing for any oversight he might commit, as he 
had never at any previous Meeting of the British Association presided over the 
Mechanical Section. He was happy, however, that there could be no danger of serious 
ors on his part, as there were able men on both sides of him who had made Civil 
gineering their special study. He proceeded to say that the question had some- 
es been asked why a Mechanical Section was necessary ; might not all mechanical 
estions be conveniently discussed in the Mathematical and Physical Section? To 
i question, on some occasions, an answer has been returned. It may at once be 
that it has been found eminently useful to have separate Sections for each di- 
department. It is only under such an arrangement that discussion can be really 
: ctive in bringing out new truths. Ifa considerable portion of the Section is not 
‘intimately acquainted with the subject in all its details, what prospect can there be of 
