'NATURE 
351 
mistake, certainly ; though perhaps these phenomena 
e of little service in his time. Having become a fen- 
‘sionnatre of the Academy in 1760, he resigned the editor- 
ip of the Connatssance des Temps to Joseph-Jeréme Le 
cois de Lalande, 
De Lalande, born at Bourg-en-Bresse, July 11, 1732, 
was sent at the age of 20 to Berlin, under the patronage 
of Le Monnier, his master, to take observations of the 
moon, which, combined with those which La Caille at 
that time effected at the Cape of Good Hope, were the 
means of giving the parallax of that planet. On his re- 
turn he was presented to a place vacant for many years 
in the Academy, and shortly after, in 1760, he was 
entrusted with the editorship of the Conmnatssance des 
emps. A distinguished astronomer, possessing a tho- 
rough knowledge of all the advances which had been 
e during later years in astronomical science, Lalande 
ry much improved the work of which he had charge. 
e shall mention the most important of the changes 
which are due to him. 
His first care was to take for the basis of his calcula- 
tions new tables, more exact than those which Godin had 
continued to employ. He employed for the sun the tables 
the Abbé of La Caille ; for the moon, those of Tobie 
Mayer* ; for the planets, the tables of Cassini ; and for 
the eclipses of the satellites of Jupiter, those of the Swede 
Wargentin, of which he had published a new edition. 
The rising of the sun and the planets is calculated for the 
true noon of each day ; but, says Lalande, “the Connais- 
ance des Temps being intended mainly for astronomers, 
the positions of the moon are given for the instant of her 
passage across the meridian.” The following year, how- 
" ever, “ on account of the inconveniences attending such a 
_ mode of indication,” this astronomer resolved to give the 
longitudes for midday and midnight of each day. Finally, 
‘in a short and well-written memoir appended to the Cow- 
naissance des Temps,t+ he investigated the different 
methods for finding the longitude at sea by a single ob- 
Servation of the moon. Some years later he restored the 
- announcement of the occultation of stars. 
In 1774, the Connaissance received from Jerome Lalande 
a most important improvement, which was the means of 
' making this work, hitherto almost exclusively intended 
- for astronomers, of great use to mariners. But, before 
_ stating in what this modification consisted, some historical 
details are necessary concerning one who was the real 
' pioneer, and at the same time one of the glories of French 
astronomy in the 18th century. 
_ 1n1737,the savant Fouchy presented to Cassiniof Thury, 
son and successor of the first director of the Observatory 
of Paris, celebrated for his fine work on “The Size and 
_the Figure of the Earth,” a young deacon of 23 years, 
ho, alone, without instruments and almost without 
ooks, had acquired a remarkable astronomical educa- 
m. Cassini welcomed the frotégé of Fouchy, lodged 
lim at the Observatory, and allowed him to take part in 
this work. This young Abbé was Nicolas-Louis de la 
Caille, born on March 15, 1713, at Rumigny, near Rozoy, 
\ Thiérache. J. D. Maraldi, grand-nephew of Cassini 
_ the first, and who also lived at the Observatory, became his 
friend, and a year after his arrival (1738), La Caille made 
_ along with him the geographical description of the coast 
of France, from Nantes to Bayonne ; in 1739 La Caille 
took part in the work connected with the meridian of 
France.[ Shortly after, Dr. Robbes nominated him pro- 
‘fessor of mathematics at the Mazarin College. He insti- 
tuted a small observatory where he made a very large 
number of observations of rare precision, In 1741, at 
* “a Tabularum motuum solis et June et longitudinum methodus pro 
? oy Lalande afterwards regularly followed the custom of accompanying the 
Connarssance des Temps with short astronomical memoirs, entitled “ Addi- 
tions to the Connaissance des Temps.” This custom has continued to the 
Present day. 
ni 
. 
lished by La Caille in x744, and bore the name of Cassini de Thury. 
1 The work done by Cassini de Thury, Maraldi, and La Caille, was pub-” 
the age of 27 years, La Caille entered the Academy of 
Sciences. 
In 1744 the astronomer of the Mazarin College pub- 
lished the first volume of a series of Ephemerides, entitled 
“Ephémérides des monuments célestes depuis 1745 
jusqen 1754,”in which he was the first to give—and 
Lalande afterwards imitated him in the Conxnaissance des 
Temps of 1760—the distance of the sun at the equinox, 
or, what amounts to the same thing, the right ascension 
of the sun in time. 
Some years later, in 1749, La Caille proposed to the 
Academy that he should spend a year at the Cape of 
Good Hope, for the purpose of making an accurate 
catalogue of the stars of the southern sky, intended to 
replace the first rough sketch made in 1677, by Halley, 
at St. Helena; to measure the parallax of the moon, of 
Verius, and of Mars, by means of comparative obser- 
vations made simultaneously in Eurepe; and finally to 
determine carefully the geographical position of the 
Cape of Good Hope.* 
The proposal of La Caille was adopted, and the States- 
General of Holland having given their assent, La Caille 
set out in 1751, after having published the list of stars 
which he wished to be observed by the European astro- 
nomers, for the purpose of rendering his voyage fruitful 
in scientific results. We do not intend to recount all the 
incidents of this expedition. Let us, however, mention a 
fact which illustrates well the character of this astrono- 
mer, “reserved, modest, and disinterested.” He received 
for his expedition, the purchase of instruments, and other 
expenses, for his maintenance and that of an artist, the 
sum of 10,000 livres; on his return, he found he had 
spent only 9,145 livres. He scrupulously carried back the 
balance to the royal treasury; the officials, surprised, 
would not accept it. “You require it,” they said to him; 
“it will take it to remunerate you.” Moreover, when he 
set out from the Cape, the minister had charged him to 
make maps of the Isles of France and of Bourbon, which 
were not comprised in the original plan, and “ for which 
most others would have asked, and certainly obtained, a 
supplementary indemnity.” + 
The observations made during this expedition (1751 
and 1752) by La Caille with his telescope of 26 inches 
focus, and an inch and a half aperture, were published by 
himself, and after his death, by Maraldi, in 1763, under 
the title, “ Ccelum australe stelliferum, seu observationes 
ad construendum stellarum Australius catalogum insti- 
tutee, in Africa ad Caput Bonze-spei, 4 Nicolao-Ludovice 
De La Caille.” 
A new edition of this catalogue was published in 1847, 
under the superintendence and at the expense of the 
British Association and the British Government, under the 
editorship of Messrs. Bailly and Henderson, the latter, at 
the time, Director of the Edinburgh Observatory. t 
But, besides, this voyage to the Cape of Good Hope 
had a mostimportant result. During the two journeys, La 
Caille tested and compared all the methods employed till 
then to determine longitude at sea. Among these he 
noted that which the celebrated Halley had given in 1678, 
and which is based upon the observation of the distance 
of the moon from the sun or froma stare The experi- 
ments which he made in reference to it having convinced 
him of its excellence, he strongly recommended it on his 
return to France; and in his second volume of Epheme- 
rides, which commenced in 1755, he proposed a Nautical 
Almanac, in which should be found, for every hour of the 
* La Caille also purposed to observe the length of the seconds pendulum, 
the variation of} the magnetic needle, and finally the length of a degree of 
the meridian at the Cape This has since been measured under the 
equator, under the Polar Circle, and in various places in Europe; but we 
do not yet know the value of any degree in the southern hemisphere. 
In the accounts which he rendered on his return, La Caille has put 
down only five sous for his daily expenses, and as much for those of a me- 
chanician who accompanied him. 
} The Association gave 200/. and the Government 1,o00/. It is entitled 
““A Catalogue of 9,766 Stars inthe Southern Hemisphere for the beginnin, 
of the year 1750, peat the Observation of the Abbé de la Caille,” i a 
