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XLV1II. — Survey of that part of the range of Nature & Ope- 

 rations which Man is competent to Study. By G. Johnstone 

 Stoney, M.A., D.Sc, F.R.S* 



Preface. 



IN the year 1860 Professor Clerk Maxwell published, in the 

 pages of the ' Philosophical Magazine,' a remarkable in- 

 vestigation, aided by which the present writer, in that year, 

 drew up for his own information the scheme of magnitudes 

 described in the following pages, from the use of which he has 

 ever since derived advantage when studying the operations of 

 Nature, whether those carried on upon a large or on a small 

 scale. (See fig. 1). 



At the suggestion of some scientific friends he now publishes 

 the diagram, in the hope that it may prove of equal assistance 

 to others, by contributing towards the formation of a correct 

 estimate of what that little is which man can truly know ; 

 and of the contrast which necessarily prevails whenever the 

 boundless range both in time and space of each actual operation 

 in nature, is considered in its relation to the limits in both 

 directions at which any clear human knowledge concerning it 

 must stop. 



Definitions. 



When interpreting Nature's work, we are obliged frequently 

 to speak of high numbers and small fractions. To do this 

 conveniently we shall employ the affix -o to signify a decimal 

 multiple. Thus, a uno will mean some decimal multiple of 

 the arithmetical unit, that is, some member of the series 10, 

 100, 1000, &c. The uno-eighteen is to be understood as the 

 name of the eighteenth of this series : it is accordingly 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 sixteenth 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 sub- 

 multiples of a metre. Or, it may be spoken of as the tenthet- 



* From a separate copy of the Scientific Proceedings of the Royal 

 Dublin Society, vol. ix. No. 13, communicated by the Author. 



