338 



SCIENCE-GOSSIP. 



1 centilitre (el) 

 (del) 



= 1 decilitre 



=. 1 litre (1) 



= 1 dekalitre (dkl) 



= 1 hektolitre (hkl) 



= 1 kilolitre (kilo) 



inch, each side of which will be seen to be equal to 

 just over 2^ centimetres (2'54). 

 Volumes. 

 In the third dimensional measures, or measures 

 of volume and solidity, it might be expected that 

 the cube of the linear unit, the cubic metre, woixld 

 be the one chosen. This unit is, however, too large 

 for ordinaiy manipulations, although it is some- 

 times used for scientific purposes. The unit taken 

 is the c%d)ic decimetre and is called a litre. A cubic 

 centimetre is therefore a thousandth part of a litre 

 and a litre a thousandth part of a cubic metre, as 

 will be seen from the following table : — 



Table of Volumes. 

 10 millilitres or "^ 



10 cubic centimetres ) 

 10 centilitres (cl) 

 10 deciliti-es (del) 

 10 litres (1) 

 10 dekalitres (dkl) 

 10 hektolitres (hkl) 

 1 cubic inch = 16-386 cc. 



1 gallon 

 Various vessels, siich as burettes, flasks, 

 pipettes, &c., are used for measiiring 

 volumes, and some of these are shown in 

 fig. 3. Flasks and some pipettes for mea- 

 siu'ing off some one definite volume are 

 provided with an engraved ring round the 

 neck, thus marking off the exact quantity, 

 viz. : — 1 litre, 1 centilitre or 1 cubic centi- 

 metre, as the case may be. 



Other pipettes and most burettes are 

 divided throughout their length into cubic 

 centimetres or fractions of cubic centi- 

 metres, some measuring as accurately as 

 to -goth of a cubic centimetre. 

 Weights. 

 Coming now to the question of weights 

 we find there is an intimate connection 

 between these and the measures last dis- 

 ciissed. As a matter of fact, the scale of 

 weights on the metric system has been 

 compiled directly from consideration of 

 volumes. The unit of weight is the 

 gramme and it is the weight o'f one cubic 

 centimetre of water when at the tempera- 

 ture of 4° Centigrade. ( ' ) 



The gramme being too small for some 

 piu-poses, the kilogranmae is frequently used 

 as the unit. The relation between these 

 and other multiples will be seen from the 

 table : Table of Weights. 



10 milligrammes (mgm) = 

 10 centigrammes = 



10 decigrammes = 



10 grammes = 



10 dekagrammes = 



10 hektogrammes = 



1 gi-ain = -0648 grammes. 1 oz. troy 



1 lb. avd. = 453-59 grammes 



Time. 

 In the above tables we have given two out of 

 the three fundamental units that are necessary in 

 all scientific questions. These are the centimetre 

 and the gramme, to designate units of length and 

 mass. The third absolute quantity that requires 

 a unit is, of course, time, and the unit for this is 

 the same on both systems, viz. : the second. These 

 three fundamental units therefore constitute 

 what is called the Centimetre-Gramme-Second 

 system, or shortly the C. G. S. system. All other 

 quantities, such as force, work, energy, &c., are 



•610 cubic inch. 



6-102 cubic inches. 

 61-027 cubic inches. 

 -353 cubic foot. 

 3-532 cubic feet. 

 35-316 cubic feet. 

 1 cubic foot = 28-315 litres. 

 4-543 litres. 



Fig. 3. 



1 centigramme (cgm) = -1543 grains. 



1 decigramme (dcgm) = 1-543 grains. 



1 gramme (gm) = 15-432 grains. 



1 dekagramme (dkgm) = -022 lb. avd. 



1 hektogramme (hkgm) = -2204 lb. avd. 



1 kilogramme (klgm) = 2204 lb. avd. 



31-103 grammes. 1 oz. avd. = 28-35 grammes. 

 1 cwt. = 50-8 kilogrammes. 



(1) Acciu-ately speaking, tliis definition sliould include the latitude in wliich tliis weight is taken, for it must be 

 remembered that althoug-h the mass of a body is constant everywhere, its weight— or the force of atti-action between 

 it and the earth— varies with the latitude, being gTeatest at the poles and least at the equator. 



