32 



WORK OF THE CARNEGIE AND SUGGESTIONS FOR FUTURE SCIENTIFIC CRUISES 



diatoms from the harbors we visit. These exquisite 

 microscopic plants, displaying inexhaustible patterns of 

 form, are present in all the waters of the earth from 

 pole to pole. They are almost the sole food for the lar- 

 val stages of fish, and therefore are of immense impor- 

 tance. Some of the largest marine creatures use these 

 tiny plants as food. So minute are they that a hundred 

 of them might be placed side by side on the head of a 

 common pin. The harvest of fish has been increased 

 noticeably by adding silicates and phosphates to the water 

 to augment the supply of diatoms, just as nitrates and 

 phosphates are used in agriculture. The work on board 

 was planned to include a study of the relation of these 

 chemicals to the abundance of diatoms and plankton. In 

 fact, the source of silica in the surface layers of the 

 ocean, where the diatoms thrive, is not well known, for 

 the great red-clay silica deposits are sometimes sever- 

 al miles below and seem to be increasing in extent. 



In higher latitudes the diatoms show great changes 

 in abundance with change of season, for they are plants 

 and depend directly on sunlight as their source of ener- 

 gy. It is for this reason that they are found in a living 

 state only in the uppermost few hundred meters of the 

 sea, and on the bottom of shallow waters near shore. It 

 is not always realized that sunlight is totally absorbed 

 in the clearest sea water in less than a mile from the 

 surface. 



Leaving the gear box we walk aft to the Stevenson 

 meteorological shelter, which gets its name from its 

 designer, the father of Robert Louis Stevenson. Here 

 are housed some of the various instruments used in 

 studying the circulation of the atmosphere, just as the 

 oceanographic equipment is used to give us a picture of 

 currents in the ocean. There are three forms of appa- 

 ratus for measuring the changes of humidity. One is a 

 recording psychrometer, ventilated by a motor-driven 

 fan.procured in England and designed to give a continu- 

 ous record of "wet-" and "dry-" bulb temperatures. 

 From this record is calculated the degree of saturation 

 of the air by water vapor. Another is one unit of an 

 electrical-resistance psychrometer, which measures the 

 humidity at three heights over the ocean--on deck, at the 

 main crosstrees, and at the masthead. In. the control 

 room, which we shall visit later, is the automatic re- 

 corder for these three pairs of electric thermometers 

 which registers at intervals of thirty seconds the six 

 wet- and dry-bulb temperatures in consecutive order. 

 The third is of German make, and has very accurate 

 thermometers. It is ventilated by clockwork, and is 

 read directly by the eye of the observer. This is used 

 daily to check the accuracy of the other two. 



In the shelter is also kept the little instrument for 

 measuring wind velocity--the anemometer — as well as 

 the standard sea-surface thermometer and other mete- 

 orological equipment. 



Walking aft a few feet, we stand at the steering gear 

 of the ship. There is no cozy wheelhouse on the bridge 

 for the quartermaster of a sailing ship. He must stand 

 at the very stern, v/ith an unobstructed view of the sails. 

 When sailing "by the wind" his eye is glued to the weath- 

 er side of the uppermost sail; he keeps it drawing a 

 trace of wind, but never lets it fill. It is true that the 

 Carnegie had a "bridge," but this was used only by the 

 pilot when entering or leaving port, and by the lookout 

 during the night. 



The steering gear itself is a constant source of in- 

 terest to visitors, for it is one of the many features of 



the old-time windjammer to be found on the Carnegie . 

 The whole mechanism is operated by hand; a whirl of 

 the wheel to starboard brings the helm to port and turns 

 the ship itself to starboard. The old-fashioned method 

 of giving orders to the steersman, called "port" or 

 "starboard," almost wrecked us one day in Samoa, when 

 a shore pilot in a tight place overlooked the fact that we 

 did not use the modern code in which the order refers to 

 the ship's head and not to the helm. The binnacle, which 

 stands before the man at the wheel, is also a carry-over 

 from bygone days, for the compass reads in "points" 

 and not degrees. As each man finishes his two-hour 

 trick at the wheel, he calls out to his reliever: "east by 

 south half south," and not "107 degrees." 



On one side of the wheel, mounted near the rail, 

 stands the rain gage; and on the other, the evaporimeter. 

 The latter is made of glass, and is used to measure the 

 rate of evaporation of sea water from day to day. This 

 subject is part of the general investigations made of the 

 influence on climate of movements of large bodies of 

 warm or cold water. We wished to study the transfer of 

 heat between the sea and the atmosphere; and the evap- 

 orimeter, together with the electric-resistance thermom- 

 eters, gives us much needed information. 



On the taffrail around the stern is the automatic re- 

 corder for the potential gradient of the atmosphere's 

 electricity. The negative charge on the earth's surface 

 causes an electric pressure in the air increasing with 

 height above the earth's surface. Ordinarily this rate of 

 increase or gradient is in the neighborhood of one hun- 

 dred volts per meter near sea level. There are daily 

 variations, aside from the local changes due to disturb- 

 ances in the atmosphere near the ship. The chief of 

 these is a mysterious surge in the potential gradient 

 which occurs simultaneously over the whole earth. It 

 was discovered after examining observations obtained on 

 previous cruises of the Carnegie , and our aim now was 

 to collect records from widely separated geographical 

 regions to confirm this. Any attempt to discover the 

 cause for the earth's permanent negative charge must be 

 based on a knowledge of potential gradient. 



This automatic recorder gives us traces at about 

 tenfold the rate possible with the eye-reading apparatus 

 used on former voyages. B: is also very sensitive to 

 changes in the electric conditions of the air, because 

 ionium collectors are used. Ionium is an element which 

 has the property of giving "air molecules" in its 

 neighborhood an electric charge, thus turning them into 

 "ions." These ions, acting as carriers, facilitate the 

 transfer of electricity from the air to the instrument, 

 and eliminate any lag during rapidly changing conditions. 



We shall now walk forward on the port side of the 

 quarter-deck past the jaunty little dinghy hanging in its 

 davits. The control room built alongside the companion- 

 way contains many essential parts of our equipment. 

 The time -measuring device for the sonic depth finder 

 with its control panel is located here. This electric 

 sounding device, loaned by the United States Navy, is 

 made up of three important units--the oscillator, the 

 microphones, and the timing mechanism. The oscillator, 

 a large steel diaphragm set face downwards in the keel 

 of the ship near the stern, is put into periodic vibration 

 by electromagnets and produces a sound wave which is 

 reflected from the ocean bottom. The echo is picked up 

 by microphones set in the vessel's hull, and carried to 

 the headphones of the observer, who sits at the control 

 panel. An accurate time -measuring device gives us the 



