36o 
INTERNATIONAL ASTRONOMICAL UNION Proc. N. A. S. 
7. The Central Bureau shall take the necessary measures to reach its subscribers 
in all parts of the world. If necessary, special agreements shall be made for this purpose 
with observatories or secondary centers situated in other continents which may serve 
as relays. 
8. The Central Bureau shall make every effort to reduce the expenses of transmission 
to a minimum; it shall continue to employ, for this purpose, the numeric code that has 
been in use for several years. 
Notes 
A. Telegrams sent to the Central Bureau are to be addressed: 
Astra Bruxelles 
B. Subscribers are requested to inform the Director of the Royal Observatory of 
Belgium, Uccle, of the shortest telegraphic address to which messages conveying 
notices of discoveries should be sent in order to reach them. 
Reports of Committees of the American Section of the 
International Astronomical Union 
REPORT OF THE COMMITTEE ON NOTATION, UNITS, AND 
ECONOMY OF PUBLICATION 
The Committee on Notation, Units, and Economy of Publication has 
given careful consideration to these subjects, and, although it has no 
recommendations it wishes to urge upon the Union, it begs to submit 
the following remarks in support of the appointment of a similar inter- 
national committee. 
I. units 
The multiplicity of units, applying to the same kind of measurement, 
that are now used in astronomical literature, and the indefiniteness that 
attaches to some of them, suggest the need of a careful study of this sub- 
ject and international agreement as to what units should, as a rule, be 
adopted. 
Astronomical distances, for instance, are already expressed in terms 
of the kilometer, mile, "astronomical unit" (mean solar distance), light- 
year, "parsec" (distance corresponding to a parallax of 1"), siriometer 
(corresponding to a parallax of 0."2), "the unit" (corresponding to a paral- 
lax of O.'^l), megaparsec = 10^ parsecs, and, perhaps, a few other units. 
Although no other astronomical quantity is measured in so many differ- 
ent units as the stellar distance there are some whose numerical values are 
more confusing because the name of the unit employed has at least a double 
meaning. Thus the "absolute magnitude" of a star may refer to its bright- 
ness in terms of some supposed constant; or to that brightness which the 
star under discussion would show at a distance of 10 parsecs. Similarly, 
the unit of heat commonly used in certain astronomical discussions, the 
calorie, often leaves one in doubt as to which calorie is meant, the small 
or the large. 
