Chemistry and Physics. ae 
For multiplication or division by a million, the prefixes mega* 
and micro may conveniently be employed, according to the 
present customs of the electricians. Thus the megohm is a million 
ohms, and the microfarad is the millionth part of a farad. The 
prefix mega is equivalent to the affix six. The prefix micro is 
equivalent to the prefix siath. ‘The prefixes kilo, hecto, deka, deci, 
centi, milli can also be employed in their usual senses before all 
new names of units. 
to the unit of force of the C. G.S m; that is to say, the force 
which, acting upon a gram of matter for a second, generates a 
velocity of a centimeter per second. 
_ The . S. unit of work is the work done by this force, work- 
ing through a centimeter; and we propose to denote it by some 
derivative of the Greek Epyor. Fre forms ergon, ergal, and erg 
has been used in a 
fi 
The weight of a gram at any part of the earth’s surface is about 
980 dynes, or rather less than a kilodyne. : 
The weight of a kilogram is rather less than a megadyne, being 
about 980,000 dynes. 
980 
* Before a vowel, either meg or megal (as euphony may suggest), may be em- 
Ployed instead of mega. : 
Am. Jour. 8c1.—Turep Serres, Vor. VII, No. 39.—Mancn, 1874. 
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