706 REPOKT — 1891. 



method. This lesson, however, they were slow to learii, an! centuries elapsed 

 before they once more advanced along: the only correct path which Ptoh my had 

 been the tirst to tread. 



During the ' Dark Ages ' which followed the disruemberment of the Roman 

 Empire there was no lack of maps, but they were utterly worthless from a 

 scientific point of view. The achievements of the ancients were ignored, and the 

 priucipal aim of the map-makers of the period appears to have been to reconcile 

 their handiwork with the orthodox interpretation of the Holy Scriptures. Hence 

 those numerous ' wheel maps,' upon which Jerusalem is made to represent the 

 hub, whilst the western half of the disk is assigned to Europe and Africa, and the 

 eastern to Asia. 



As it is not my intention to introduce you to the archaeological curiosities of 

 an uncritical age, but to give you some idea of the progress of cartography, I at 

 once pass on to the Arabs. 



The Arabs were great as travellers, greater still as astronomers, but con- 

 temptible as cartographers. Their astronomers, fully possessed of the knowledge 

 of Ptolemy, discovered the error of the gnomon, they improved the instruments 

 which they had inherited from the ancients, and carefully fixed the latitudes of 

 quite a number of places. Zarkala, the Director of the Observatory of Toledo, even 

 attempted to determine the diflFerence of longitude between that place and 

 Bagdad ; and if his result diff'ered to the extent of three degrees from the truth, 

 it nevertheless proved a great advance upon Ptolemy, whose map exhibits an error 

 amounting to eighteen degrees. Had there existed a scientific cartographer among 

 the Arabs, he would have been able, with the aid of these observations and of the 

 estimates of distances made by careful obser\trs like Abul Hasan, to efi'ect most 

 material corrections in tlie map of the known world. If Edrisi's map (1154) is 

 better than that of others of liis Arab contemporaries, this is simply due to his- 

 residence at Palermo, where he was able to avail liiasflf of the knowledge of the 

 Italians. 



Quite a new epoch in the history of Cartography begins with the introduction 

 of the magnetic needle into Europe. Hitherto the seaman had governed his course 

 by the observation of the heavens ; thenceforth an instrument was placed in his 

 hands which made him independent of the state of the sky. The property of the 

 magnet or ' loadstone ' to point to the north first became known in the eleventh 

 century, and in the time of Alexander Neckam fl 185) it was already poised upon a 

 pivot. It was, however, only after Flavio Gioja of Amalfi (1302) had attached to 

 it a compass-card, exhibiting the direction of the winds, that it became of such 

 immediate importance to the marmer. It is only natural that the Italians, who 

 were the foremost seamen of that age, should have been the first to avail themselves 

 of this new help to navigation. At quite an early date, as early probably as the 

 twelfth century, they made use of it for their maritime surveys, and in course of 

 time they produced a series of charts upon which the coasts frequented by them, from 

 the recesses of the Black Sea to the mouth of the Rhine, are delineated for the first 

 time with surprising fidelity to nature. The appearance of these so-called compass- 

 charts, with gaily coloured roses of the winds and a bewildering number of rhumb- 

 lines, is quite unmistakable. A little consideration will show you that if the varia- 

 tion of the compass had been taken into account in the construction of these charts, 

 tbey would actually have developed into a picture of the world on Mercator's projec- 

 tion. But to deny them all scientific value, because they do not fulfil this condition, is 

 going too far. As correct delineations of the contours of the land they were a great 

 advance upon Ptolemy's maps, and it redounds little to the credit of the 'learned ' 

 geographers of a later tinie that they rejected the information so laboriously 

 collected and skilfully combined by the chart makers, and returned to the defor- 

 mities of Ptolemy. The adjustment of these charts to positions ascertained by 

 astronomical observations could have been easily effected. An inspection of 

 my diagrams will prove this to you. The delineation of Italy, on the so-calledf 

 Catalan map, is surprisingly correct; whilst Gastaldo, whose map of Italy is nearly 



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