The Cruise of the " Princesse Alice" 265 



basin is placed beyond all doubt, and it was appropriately 

 named the Hirondelle Deep. The temperature of the secluded 

 water, 5 C., enables us, by comparison with temperature 

 observations at different depths outside, to fix within pretty 

 narrow limits the depth below the surface of the ocean where 

 the lowest "col" occurs which leads from the interior of the 

 basin across the lip to the outer oceanic world, and it must be 

 between 850 and 900 fathoms. 



There is no doubt that other and similar enclosed basins 

 occur amongst the Azores ; but they remain for future investi- 

 gation. Chapters might be written about this interesting 

 feature which is common to all archipelagoes, as witness the 

 \V--st Indies and the seas of the further East, such as the Celebes 

 and the Sulu seas. Nearer home we have the Mediterranean 

 with the original archipelago and the Red Sea. Indeed the 

 further we proceed with the detailed sounding of the ocean 

 the more such features do we discover. But, as the normal 

 change of temperature with increase of depth decreases, it 

 becomes more and more difficult to detect such features by 

 temperature observations alone. It is, however, quite evident 

 that the bottom of the ocean is not a smooth spherical surface; 

 and, if it is not, then it must consist of heights and 

 hollo 



As a complimentary feature to the Hirondelle Deep the 

 Prince discovered a few years ago the Princesse Alice bank, a 

 very extensive shoal lying to the south-west of the island of 

 Fayal. A few days were now spent in making further sounding 

 on it. For some years it has proved a most productive fishing 

 ground; and this year all tin- trapping resources of the "Prin- 

 cesse Alice" were put forth, hut in vain. Hardly anything of 

 any kind was caught by any mean-. This was certainlv 



rkable. because the extent of tin- bank ami it- di-t.tn<< 

 fi'.m tin- islands are both so great that there can be no question 

 of over-h-hm-. Moreover, oceanic shoal- an always good 

 h-hin- ground-, and h-hiii- on them reduce! it-elf to pir 



ind hauling in lines as fast as possible. Yet here the 

 would neither ^o into net- noi md it almost seemed 



nahle to -upp'^r that tln-v h.id gone elsewhere. 



