80 Scientific Proceedings, Royal Dublin Society. 
this series : it isaccordingly the number represented by 1 followed 
by eighteen ciphers. Similarly a metro will mean some decimal 
multiple of the metre, and the metro-sixteen will mean the six- 
teenth of this series of metros. In other words, it is a uno- 
sixteen of metres. So, again, we shall use the syllable -et for 
decimal sub-multiple. Thus the sixthet will mean the sixth of 
these -ets, that is, a unit in the sixth place of decimals. In this 
nomenclature, the tenthet of a metre is the same as the tenth-metret, 
i.e. the tenth of the series of metrets or decimal submultiples of 
ametre. Or, it may be spoken of as the tenthet-metre, using this 
word as an abbreviation for “tenthet ofa metre”; just as we may 
say half-ounce or quarter-inch.' 
Maxweu’s DETERMINATION. 
In the year 1860, the late Professor Clerk Maxwell published 
the first determination made by man of any actual molecular 
interval.? The principles upon which he proceeded may be 
described as follows :—In accordance with the Kinetic Theory of 
1Tt is as necessary to be able to write the quantities we have to deal with in some 
convenient form, as it is to be able to describe them briefly. The usual plan is to 
employ positive and negative powers of 10 1o express decimal multiples and submultiples. 
Another contrivance is to represent them by Roman numerals in the way indicated by 
the following examples :— 
As specimens of decimal multiples, let XVI (a uno-sixteen) mean 1 followed by 
sixteen ciphers, and let 4 VII (four uno-sevens) mean 4 followed by seven ciphers. 
In multiples the Roman numeral indicates the number of ciphers. 
Similarly, to represent sub-multiples, let VIII+ (an eighthet) be used as the symbol 
for a unit in the eighth place of decimals, and let 6. XIII* (six thirteenthets) mean 6 in 
the thirteenth place of decimals. In sub-multiples the Roman numeral indicates the 
decimal place. 
In manuscript it is more convenient to employ a little curved line, the left-hand 
half of the letter 0, instead of the letter ¢, which has been used in the last paragraph 
for the convenience of the printer. The small curved line is easily written, and it is 
appropriate, as it is the symbol in Pitman’s Phonography for the group of letters 
tht, or thet. 
We may extend the same convention so as to write in a condensed form multiples 
and submultiples of the metre, &&. Thus m XVI, 15 m X, [Xtm, and 7 VIIItm, will 
mean a metro-sixteen, fifteen metro-tens, a ninthet-metre (or ninth-metret), and seven 
eighthet-metres (or seven eighth-metrets). 
When once we have got accustomed to this use of the Roman numerals, they will 
be found to work more conveniently than the positive and negative powers of 10, whicb 
are usually employed. 
* Philosophical Magazine for 1860, vol. xix. p. 19, and vol. xx. p. 21. 
