208 THE RANGE OF NATURE'S OPERATIONS. 



ingly the number represented by 1 followed by 18 ciphers. Similarly 

 a metro will mean some decimal multiple of the meter, and the metro- 

 sixteen Avill mean the sixteenth of this series of metros. In other 

 words, it is a uno-sixteen of meters. So, again, we shall use the 

 syllable -et for decimal submultiple. 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 meter is the same as the tenth- 

 metret, i. e., the tenth of the series of metrets or decimal submultiples 

 of a meter. Or, it may be spoken of as the tenthetrmeter, using this 

 word as an abbreviation for "tenthet of a meter;" just as we may say 

 half ounce or quarter inch.^ 



maxwell's determination. 



In the year 1860 the late Prof. Clerk Maxwell pul)lished 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 gas, a gas consists of an enor- 

 mous swarm of little missiles, all alike in each kind of gas, though 

 differing from one gas to another. These molecules dart about among 

 one another with almost incredible activity, and are, to use Maxwell's 

 simile, like the individuals of a swarm of bees which furiously make 

 short flights in every direction, while the swarm as a whole is either 

 stationary or quietly sailing along. In a gas each molecule dashes f or- 



' It 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 visual plan is to 

 employ positive and negative powers of 10 to express decimal multiples and submul- 

 tiples. Another contrivance is to represent them by Roman numerals in the way 

 indicated by the following examples: 



As specimens of decimal nuiltiples, let XVI (a uno-sixteen) mean 1 followed by 

 sixteen ciphers, and let 4 VII (four imo-sevens) mean 4 followed by seven ciphers. 

 In multij)les the Roman numeral indicates the number of ciphers. 



Similarly, to represent submultiples, 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 subnniltiples 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 "o," instead of the letter "t," which has been used in the last para- 

 graph 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 submultiplesof the meter, etc. Thus m XVI, 15 m X, IX' m, and 7 VIII' m 

 will mean a metro-sixteen, fifteen metro-tens, a ninthet-meter (or ninth-metret), and 

 seven eighthet-meters (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, which 

 are usually employed. 



■■'Philosophical Magazine for 1860, Vol. XXI, p. 19, and Vol. XX, p. 21 



