June 30, 1898] 



NATURE 



201 



have just built another one still more powerful, of 1400 

 tons, also called Princess Alice. Thus the love of science, 

 and the successful combat of the difficulties met with in 

 its employment in researches at sea, enlarges constantly 

 the horizon and demands more powerful means. 



I began by trying to find out experimentally how the 

 currents moved on the surface of the Atlantic, and for" 

 this purpose I dropped, in three different cruises, 1675 

 floats between Europe and North America. These floats 

 were mostly a strong glass bottle protected by a sheet of 

 brass, ballasted so as to keep just at the level of the 

 surface, and containing a document written in several 

 languages to invite the finders to return it with particulars 

 as to place and date. 



Out of these, 226 had been returned to me up to the year 

 1 892, when I drew, by working scientifically the course that 

 each of them had probably been following, a definite 

 map of the currents. And I may add that this result is 

 certainly very near the truth in its general lines, because 

 the elements employed have always been numerous for 

 each region. 



Fig. 2.— The s 



id Princess Alice. 



The floats have landed on almost all the shores of the 

 North Atlantic, from the North Cape to the south of 

 Morocco, along Central America, and on the islands 

 of Canaries, Madeira, Azores, Antilles, Bermudas, 

 Shetlands, Hebrides, Orkneys and Iceland. Not one 

 lias appeared as far south as the Cape Verd islands. 



They show an immense vortex which begins towards 

 the Antilles and Central America with the Gulf Stream, 

 which issues from the Gulf of Mexico, and with the 

 equatorial current ; passing the banks of Newfoundland 

 at a tangent, it turns to the east, approaches the 

 European coasts, and runs southward from the Channel 

 to Gibraltar, after having sent a branch which runs along 

 the coast of Ireland and the coast of Norway as far 

 as the North Cape. 



It then retiirns to the west, encircling the Canaries. 

 Its centre oscillates somewhere to the south-west of the 

 .Azores. 



My observations enabled me also to establish a very 

 good average for the speed at which these floats have 

 been travelling in the different sections of the vortex, and 

 for every twenty-four hours. 



Between the Azores, France, Portugal and the Canaries : 

 5" 18 miles. 



NO. 1496, VOL. 58] 



From the Canaries to the Antilles, the Bahamas, and 

 as far as the Bermudas : lo'ii miles. 



From the Bermudas to the Azores : 6'42 miles. 



The mean speed for the North Atlantic is 4*48 miles. 

 These values being under rather than over the truth. 



When I began to work on the bottom of the sea to 

 study animal life, as constant sounding is required for that 

 purpose, I found that most of the sounding machines in use 

 were defective, and I had one constructed according to 

 my own ideas. It is completely automatic in all the 

 details of its action, so as to allow a single man to take a 

 sounding at any depth ; the line that I have used for 

 four years is no longer a steel wire, but a steel cable 

 made up of many very thin wires ; it is, therefore, 

 stronger and more pliable. It is paid out at the required 

 speed, hauled up again, dried, greased, and regularly 

 rolled up on a drum by an automatic guide. The brake 

 is a powerful spring. 



Among the observations for which this machine is 

 wanted, I will mention those concerning the temperature 

 of the water at different levels. I am using, to obtain 

 them, a thermometer designed for my cruises by Mr. 

 Chabaud, a French instrument maker. It is very much 

 like Negretti and Zambra's pattern, but the part of the 

 tube containing the mercury reservoir is recurved so as 

 to prevent the mass of this metal forcing itself by its 

 own weight through the constricted angle which serves 

 to break the column ; and such an accident used tcv 

 happen now and then. 



When I went into the study of the density of the 

 water, I found that Buchanan's bottle was the best for 

 collecting samples of the stratum nearest to the bottom. 

 But to obtain samples at any intermediate depth. Dr. 

 Jules Richard, chief of my laboratory, has designed a 

 thoroughly trustworthy instrument with which we have 

 been able to study the gases contained in these samples,, 

 and to demonstrate that they are not dissolved in the 

 depths at any other pressure than they are at the surface. 

 This instrument can be shortly described by saying that 

 it is a bottle filled with mercury, and inverted with its 

 neck dipping into a dish also full of mercury. In this 

 position it is sent along a steel cable as far as the 

 required depth, where it meets a platform, and where 

 a mechanical action raises the neck of the bottle over 

 the mercury of the dish. The mercury of the bottle then 

 runs out into the dish, and water takes its place. Soon 

 after this, a messenger sent from the ship reaches the 

 instrument, and acts so as to dip again the neck of the 

 bottle into the dish containing the whole of the mercury. 

 In this last position the instrument can be hauled up 

 without any risk of the sample of water being mixed with 

 outside water ; and if there was any gas dissolved in it 

 at a high pressure (which was not the case in my ob- 

 servations), it would gather on the surface of the sample, 

 as this pressure would diminish as the instrument came 

 nearer to the surface of the sea. This research led 

 Dr. Richard to announce in 1895 ^^e presence of argon 

 in the swimming bladder of certain fishes. 



Very soon after this, I had the satisfaction of present- 

 ing the French Academy of Science with very interesting 

 observations made by M. Knudsen during the cruises of 

 the Danish steamer Ingolf. This investigator proved by 

 analyses of samples of water made in situ that pre- 

 dominance of animal or vegetable life in any part of the 

 sea causes the variations in the amount of contained 

 oxygen or carbonic acid. 



One of the most difficult questions to investigate is the 

 penetration of light in the depth. Photographic plates 

 turned towards the heavens have been exposed by 

 Hermann Fol, and impressed as deep as about 200 

 fathoms. I have myself used, as far as about 90 feet, an 

 instrument invented by Dr. Regnard for my experi- 

 ments ; it is a cylindrical box with a narrow slit in the 

 direction of its length. Inside is a sensitive paper, which 



