72 



The National Geographic Magazine 



which is below that of fog, in which 

 percentages for a force of 8 and over 

 of the Beaufort's scale — from 40 to 100 

 miles an hour — are given in 5° squares. 

 No vessel other than a regular high- 

 powered liner, unless absolute necessity 

 demands, takes a route in which such 

 gales are frequent, on account of the 

 danger to life and property, the wear on 

 the vessel, and the consequent delay. 

 This sub-chart tells them the only things 

 they want to know — how to avoid the 

 stormy area and what route to choose. 



The best routes for low - powered 

 steamers, from the English Channel to 

 the Gulf and from Gibraltar to New r 

 York, are also shown. The latter, for 

 instance, is longer in distance than a 

 direct route. Experience has shown, 

 however, that by reason of encounter- 

 ing more favorable winds, seas, and cur- 

 rents, it is shorter in time, with much 

 less wear and tear on the vessel and 

 crew. 



Down in the lower left-hand corner 

 are some red symbols to designate ice- 

 bergs and field ice. No bergs or field 

 ice were reported during January, so 

 none are indicated on the accompanying 

 chart. On the pilot charts of the sum- 

 mer months, however, the region above 

 and about the Grand Banks is dotted 

 with these little red symbols. If we 

 were issuing a pilot chart of the south 

 Atlantic Ocean for this month, these ice 

 symbols would be very numerous in its 

 southern portion. 



You may remember that it was not 

 many years ago that we had frequent 

 reports of vessels colliding with ice- 

 bergs ; but such is now very much less 

 the case, principally due, I feel that I 

 can say with absolute truthfulness, to 

 the efforts of the Hydrographic Office, 

 as a result of which the transatlantic 

 lines were, some '3'ears ago, induced to 

 adopt regular lanes of transit to and 

 from England and the United States — 

 lanes which take them over a safer 

 route, in that it is practically clear of ice. 



Over on the right-hand side of the 

 pilot chart is a sub-chart of isobars and 

 isotherms for the month of February, 

 showing the average heights of barom- 

 eter and temperature to be expected, 

 and indicating, by reference to the areas 

 of low and high barometer, what move- 

 ment of the atmosphere may generally 

 be looked for. The intelligent mariner 

 knows that any marked deviation from 

 these normal values denotes a change 

 in weather. 



Above this sub-chart will be found 

 a forecast — not a prediction — of the 

 weather, the average of thousands of 

 observations taken during the past fif- 

 teen years. 



The main or sea part of the chart 

 is divided up into 5 squares, in the 

 center of each one of which will be 

 found a small circle from which radiate 

 arrows, each one pointing towards the 

 center. These arrows indicate the di- 

 rection in which winds ma} r be expected 

 to blow, the number of feathers indicat- 

 ing the force by Beaufort's scale. Take 

 the example" noted in blue under the 

 heading of "Prevailing Winds and 

 Calms," at the bottom of the chart on 

 the left side. The arrows fly with the 

 wind, and the number of hours in each 

 one hundred during which the wind 

 may be expected to blow from that 

 direction is found by transferring the 

 length of the arrow to the scale below, 

 the number of feathers indicating the 

 force. Thus, in this example, we will 

 in each one hundred hours expect to 

 find a northeast wind with a force of 

 3 for 18 hours ; an east wind, force 

 of 3 for 10 hours; a southeast wind, 

 force of 4 for 24 hours; a south-south- 

 east wind, force of 3 for 25 hours, and 

 a southwest wind, force of 3 for 10 

 hours. The figure 13 within the cen- 

 tral circle indicates 13 hours of calms, 

 light airs, and variable winds. 



The small black arrows point out the 

 average set of currents, whether regular 

 or drift. 



