La Caille was an astronomer whose observations will have the highest value as long as astronomy is cultivated, which cannot be said of others, his superiors in originality of discovery. Lalande said of him that he alone had made more observations than all his contempo raries put together, which Delambre states would be no exaggeration if spoken of the twenty-seven years during which he laboured ; but though his utility was much increased by his extraordinary activity, industry, and honesty, yet his reputation was still more indebted to the genius which he displayed in produciog exactness out of imperfect instruments. Delambre remarks that the repeating circles of Lenoir and Reichenbach have not been able to correct the latitude of the Observatory of Paris as determined by La Caille. He also says :— "Having been called upou by singular conjunction of circumstances to go over and verify a great part of the labours of La Caine, after having reviewed with the greatest care all his stars, made loug researches on refraction, constructed new solar tables, measured the meridian of France, and had io my hands for many years all the manuscripts of La Caille, I never followed him one step of his track without feeling increased admiration and esteem for a savant who will always be the hononr of French astronomy." Delambre is, us we have seen, a severe critic in all quarters, and never shows much, if any, national bias in great questions : an eloge from him is history.
The writings published by La Caitle are as follows :-1745-54, ' Ephemerides 1746, ' Legone Eldmentaires d'Astronomie, Geom., et Phys.,' reprinted in 1755, 1761, and in 1780, with notes by Lalande ; translated into English by Robertson, 1750; his first observations for 1743 are io the ' Memoirs' of the Academy, which appeared in 1748 ; 1750, Lecons lldmentairee d'Optique,' a work which maintained its ground a long time, but only for want of a better ; 1750, 'Avis aux Aatronomes,' Ste., a pamphlet recommending the corresponding
observatione to be made in Europe while he was in the south ; 1753, Observations wade at the Cape for Parallax of Moon, Mara, and Venus; 1755-64, Ephemerides,' ou the model of which, according to Lalaude, our ' Nautical Almanack ' was constructed; 1757, 'Fuudamcnta Aistronomim: among many other things this contains a catalogue of 397 stars (northern), of which Delambre says that it coat more trouble than any other catalogue ever gave its author ; 1758, 'Tabula) Solares,' the beat up to the time of Delambre and Zach. But the first work of La Caillo (according to Delambre, and omitted by Lalaude) was an edition of, or commentary on, the tract of Cotes, entitled ' Estimatio Errorum, &c., the first attempt to apply the theory of probabilities to the determination of the most probable mean of observations. La Caille was an astronomer who made his own head supply the deficiencies of his workmen's hands.
The posthumous works of La Caille were as follows :-1765-74, 'Ephemerides,' containing also a catalogue of 515 zodiacal stars; 1763, 'Journal Hiatorique du Voyage fait au Cap de Bonne Esperancef 1763, Ccelum Australe Stelliferum; the record of his observations in the southern hemisphere. It contains observations of more than ten thousand stars, with a catalogue of 1942 principal stars, which catalogue is also in the ' Memoirs' of the Academy for 1752.