THE EVOLUTION OF THE MARINE CHART 35 



of indicating direction by lines radiating from a centre was of 

 ancient date, and is known to have been occasionally used in 

 medieval times. In the earlier instance, however, the division 

 of the circle was into twelfths and not into eighths, as on the 

 compass rose. The best answer to these objections lies in a 

 closer examination of the purpose of this system of direction 

 lines, which has been discussed above — for it provided a 

 method of determining a course which could not be found 

 from a written portolario, and this method depended upon the 

 use of the compass. 



In attempting to determine the date of the first appearance 

 of these charts, therefore, we can be guided to some extent by 

 what is known of the history of the compass. A primitive form 

 was probably in use in the twelfth century, consisting of a 

 needle thrust through a piece of wood and floating in a bowl 

 of water. An improved type appeared about the year 1250, in 

 which the water was dispensed with, the needle being balanced 

 on a pin. With the addition somewhat later of the compass 

 card, the compass as we know it today had in essence evolved. 

 This development may well have been decisive in the evolution 

 of the portolan chart. By means of the card, bearings could be 

 taken with comparative ease and rapidity. Keeping this in 

 mind, we may turn to consider the other evidence for dating. 

 The * Carte Pisane' was probably drawn towards the end of 

 the thirteenth century, and the first dated chart is from the 

 year 1311. Since their form had then become stereotyped, the 

 original can scarcely be later than the third quarter of the 

 thirteenth century, and it is about that time that the earliest 

 references in literary sources to sea charts are found. 



There is an incident on record which shows that charts 

 were in use in a.d. 1270. In that year, King Louis IX embarked 

 on the Mediterranean for his crusade in North Africa. Soon 

 after setting sail, the fleet was dispersed by a prolonged storm. 

 When it had passed, the King was anxious to know the position 

 of his ship, and the pilots were able to point out on a chart that 

 they were approaching Cagliari. Writing at about the same 

 period, Raymond Lull includes the chart among the instruments 

 employed by seamen. We may therefore assume that the 

 portolan chart originated in the period 1250-75. 



