154 ASTRONOMY. 
_ The following years were also to begin with the midnight preceding the true 
autumnal equinox. This new French year was divided into 12 months of 
30 days, and to complete the number of days, five, or in leap year six sup- 
plementary days (jours complémentaires), were added. Instead of weeks, 
the months were divided into three decades of 10 days each. These ten days 
were called Primidi, Duodi, Tridi, Quartidi, Quintidi, Sextidi, Septidi, 
Octidi, Nonidi, and Decadi. The nomenclature of the months was te! 
from the characteristics of the seasons, as follows :— 
For Autumn: Vendemiaire, or vintage month (October) ; Brumaire, or 
cloud month (November) ; Frrimaire, or frost month (December). 
For Winter : Nivése, or snow month (January) ; Ventdse, or wind month 
(February) ; Pluvidse, or rain month (March). 
For Spring: Germinal, or growth month (April); Floréal, or bloom 
month (May); Prazréal, or meadow month (June). 
For Summer: Messidor, or harvest month (July); Thermidor, or heat 
month (August) ; Mructidor, or fruit month (September). 
The additional days are attached to this last month, and have the follow- 
ing appellations:—Ist, Méte du génie; 2d, Fete du travail; 3d, Féte des 
actions ; 4th, Féte des recompenses ; 5th, Fete de lopinion. 
In addition to what has already been said, every day of the year had its 
especial name, which, instead of being,taken from some saint, was derived 
from objects of agriculture appropriate to the time on which the days fell. 
This calendar, however, lasted only 12 years, for Napoleon abolished it by 
a Senate decree of September 9, 1805. 
ASTRONOMICAL INSTRUMENTS ; OBSERVATORIES. 
80. Astronomical instruments embrace all the apparatus which the 
practical astronomer needs in his observations of celestial phenomena, to 
impart to them that accuracy and certainty so necessary as the basis of 
delicate calculations, as also to find objects in the heavens invisible to the 
naked eye. Astronomical instruments have two purposes: the one is to 
afford a clear understanding of those objects and phenomena of the heavens, 
which, on account of their distance or minuteness, are either imperfectly 
or not at all visible to the naked eye; the other purpose is the accurate 
measurement of various angles and spaces. The following may therefore 
be considered as the most important astronomical instruments :—Transit 
Instrument, Equatorial, Refractor, Meridian Circle, Universal Instrument, 
Comet Seeker, Heliometer, Simple Circle, Theodolite, Multiplication Circle, 
Reflecting Sextant, Barometer, Thermometer, Pendulum Clock, Chrono- 
meter, &c. Of the more ancient instruments, only the Zenith Sector and 
Mural Quadrant are retained at the present day; all the rest, as, for 
example, the Octants, Quadrants, Telescopes without tubes, &c., are con- 
signed to deserved oblivion. 
The following are the names of some artists distinguished for the 
excellence of tlie astronomical instruments constructed by them. Those 
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