THE MARINER'S COMPASS. 259 



to give a long description of it. Its history is unknown. The Chinese 

 seem to have been aware of its usefulness long before the western nations 

 adopted it. It was about the time of the Crusades that it was brought into 

 western prominence, but was not generally known till the thirteenth century. 

 Chinese writings ascribe to the compass a great antiquity; they maintain 

 that it was discovered two thousand five hundred years before the Christian 

 Era, and used for travelling on land. But, according to other accounts, it 

 was not used at sea till the year 300 A.D. 



The Chinese put the south first when speaking of the points of the 

 compass, and in the Chinese empire and Thibet west goes likewise before 

 east. So the imperial edifices in China face the south, and the needle, in 

 their expression, points south and north not as we say, north and south. 

 The antiquity of the compass may be inferred from the recorded fact in 

 Chinese chronicles, written in the second century before the Christian Era, 

 that nine hundred years previously to the date of the chronicle the Emperor 

 gave magnetic cars to certain ambassadors to guide them home in safety. 

 These cars were fitted with a magnetic needle which communicated with a 

 figure. Its outstretched hand and finger followed the compass-direction, 

 and pointed out the way. 



The Chinese subsequently (in the twelfth century) suspended the needle 

 by a thread, and it is said their philosophers at that time noticed the varia- 

 tion of the needle. But Columbus first, in 1492, and Cabot, in 1540, 

 certainly remarked it in Europe. It is to Marco Polo that we are indebted 

 for the direct introduction of the needle into Europe, although it probably 

 had been in use in the Levant previously, for we have seen a quotation by 

 an Arab writer, who, in 1242, described the needle as being used at that 

 time on his voyage from Tripoli in Syria to Alexandria, two years previously. 



Friar Bacon possessed a loadstone, and there are many instances in 

 which it is referred to in ancient writings. The inventor of the compass we 

 cannot trace, but no doubt exists as to its being of Chinese origin. 



The ordinary compass is shown in the illustration herewith (fig. 265). It 

 consists of a magnetized needle, suspended freely, and fixed to a circular card, 

 which is divided and subdivided into thirty-two points, as in the cut. This 

 compass is suspended upon gimbals to keep it in an upright position when 

 the vessel rolls or plunges. The gimbals are concentric rings, the compass 

 being fastened to the inner one, and keeps its position in all weathers. It 

 is then enclosed in the binnacle, a glass receptacle. The card moves with the 

 needle which points north. There is a dark line (lubber line) which indicates 

 the ship's course, and when sailing the steersman must keep that line opposite 

 the compass direction-point which indicates the course. At night a lamp is 

 lighted in the binnacle, and the card being transparent and the points opaque 

 they are easily seen. 



The magnetism of iron ships has a tendency to disturb the needle, and 

 many suggestions have been made and discussed with a view to obviate this. 

 To put the compass at the mast-head was one, to surround the compass 



