MEMOIR OF C. F. BEAUTEMPS-BEAUPRE. 131 



northern rocks of the Passage du Four, (Fiuistcrrc,) where operations had 

 stopped ill 1818, and tlms were completed the materials for the fifth and sixth 

 parts of the Pilate Francais, which appeared in 1842 and 1844. The six 

 atlases contain twenty-one general charts, sixty-five special charts, thirty-one 

 pl»ns of double elephant size, fifteen of half elephant, and fourteen of quarter 

 elephant size, two hundred and seventy-nine tables of surveys taken of the 

 principal dangers of the west and north coasts of France, and one hundred and 

 eighty-four tables of high and low water observed during the progress of the 

 twenty seasons spent upon the same coasts. The account ( C Expose, &c.) 

 of these hydrographical labors, executed under his orders, was so drawn up by 

 M. Beautemps-Beauprc as to serve as the complement to the second chapter of 

 the appendix attached to the first volume of the voyage of d'Entrecasteaux. 

 In justifying this form of composition, he pleads that, when that appendix was 

 published, his practical knowledge of the best means for reconnoitring maritime 

 obstructions could not be so positive as that acquired during his first ten cam- 

 paigns (1817 to 1S27) on the coasts of France. It is certain, nevertheless, that 

 in everything essential his method was definitely fixed at the time of the pub- 

 lication of d'Entrecasteaux's voyage in 1808 ; and in the preface to that work 

 it is thus spoken of by M. de Ilossel, an authority of undoubted competency : 

 '* Navigators will in general find in this appendix hydrographic instructions of 

 a far more complete nature than any heretofore published. ^I. Beautemps; 

 Beaupre has here given also several expeditious methods for sounding a coast 

 and marking the depths on the chart. These methods, of which he availed 

 himself for his operations conducted on the coast of France, (before 1808,) by 

 order of the minister of marine, are so useful that it would be unjust to with- 

 hold them from navigators, as well as those of which he made use during the 

 campaign." 



From these judicious observations of one of the masters of hydrographic 

 science, it will readily be inferred that the operations Avhich M. Beautemps- 

 Beaupre conducted on the coasts of France differ in several essential particulars 

 from those with which he was habitually occupied in the voyage of d'Entre- 

 casteaux. In the latter, which pertain generally to what is called surveying 

 under sail, the end principally in A'iew was to fix the position of the remarkable 

 objects seen on the land, capes, mountains, &c., by means of observations 

 directed towards those objects from certain points in the course of the ship, de- 

 termined with especial care. The operations on the coasts of France, within 

 an extent generally less wide and with much less rapidity, had in view to fix 

 various points of the sea, rocks, places of sounding, &c., with reference to cer- 

 tain objects determined on land, mountains, steeples, semaphores, and other 

 signals. This was almost an inverse operation to the preceding ; yet this also 

 required numerous admeasurements of anglos, which were obtained with the 

 same reflecting circle, and the geometric constructions were derived essentially 

 from the same trigonometric principles, although the proposition of the " problem 

 of three points" was here more frequently employed. 



As the bearings taken from the sea were directed upon all the remarkable 

 objects of the land, it was necessary that the position of these should be deter- 

 mined by geodetic measurements made ashore with all the precision attainable 

 by science. For this reason a triangulation was executed on land embracing 

 all the points of the coast. This was efi'ected for the western coasts of France, 

 from Brest to Saint Jean de Luz, by M. Daussy, and for the northern and 

 southern coasts by M. Bi;gat, both members of the corps of hj'drographical 

 engineers of the marine. These triangulations have been connected with the 

 grand triangulation which serves as a base for the new chart of France pub- 

 lished by the corps of the etat-7najor, and have been found so exact that they 

 have been finally incorporated in that fundamental system. MM. Daussy and 

 Begat have deduced from their trigonometric labors a complete table of the 



