94 



SCIENCE. 



[Vol. XVIII. No 445 



place of the old stone needles, and were commonly used before 

 the time of Ch'in Shih-huang — that is, more than twenty-one 

 centuries ago. Whenever a needle happened to be made of mag- 

 netic iron, it might reveal its quality by falling into a cup of 

 water, when it happened to be atlached to a splinter of wood, for 

 example. It came in some such way to be known commonly that 

 certain needles had this quality. The great producing centre for 

 magnetic iron is T'szchou, in southern Chihli. This city was very 

 early called the City of Mercy, and the magnetic stone produced 

 there came to be known as the stone of T'szchou, and so t'szshih 

 became the ordinary name for a magnet. Later, the Chinese be- 

 gan to speak of the city as the " City of the Magnet," instead of 

 calling it the "City of Mercy." The polarity of the magnetic 

 needle would become known to the Chinese of that city and its 

 neighborhood first. The first who noticed the polarity would be 

 some intelligent person who communicated the fact as an unac- 

 countable peculiarity in an age when omens and portents were 

 diligently sought for in every natural object and phenomenon. 



The earliest author who msntions the " south pointing needle " 

 lived in the fourth century B.C. There can be no reasonable 

 doubt that the polarity of the needle was known at that time. 

 The discovery of the fact must have preceded the invention of any 

 myth embracing it. As to the discovery, there is no reason to 

 suppose it was in any way foreign, because the Chinese use an 

 enormous number of needles, and have an inexhaustible supply of 

 ironstone. But though the polarity was known, it was not turned 

 to a practical use till the Tsin dynasty, when landscapes began to 

 be studied by the professors of fengshui, or geomancy. There was 

 at that time a general belief in the magical powers of natural 

 objects. This was a Buddhist doctrine, and it took firm hold on 

 the Chinese mind of that age. The Chinese philosophers of those 

 times taught that indications of good and ill luck are to be seen all 

 through nature. The polarity of the needle would take its place 

 in this category of thought. Though it is not distinctly mentioned 

 by writers of the fourth century, yet to their disciples it became 

 an essential part o( the landscape compass which the professors of 

 fengshui all use. Kwo Pu, the founder of this system, died a.d. 

 324, and it was not till four centuries later that the fengshui com- 

 pass began to assume its present form. 



The compass used by the professors of geomancy for marking 

 landscape indication was first made about the eighth century. It 

 was of hard wood about a foot wide, and it had in the centre a 

 small well in which a magnetized needle floated on water. On 

 the compass were inscribed several concentric circles, as on the 

 wooden horizon of our globes. They embrace the twelve double 

 hours, the ten denary symbols, eight diagrams, and other marks. 

 This compass was used in preparing a geomantic report of any 

 spot where a house or tomb was to be constructed, so that the con- 

 struction might not be upon an unlucky site or planned in an un- 

 lucky manner. At the same time there was living a Chinese who 

 had studied Hindoo astronomy, and was the imperial astronomer, 

 and also a Buddhist priest. He noticed that the needle did not 

 point exactly north, and that there was a variation of 2° 95'. This 

 variation went on increasing till a century later, that is, till the 

 ninth century. A professor of geomancy then added a new circle 

 to the compass. On this improved compass the first of the twelve 

 hours begins on the new circle at 71° east of north. 



The compass, it will be observed, grew out of the old astrologi- 

 cal report or nativity paper, calculated from the position of the 

 stars, and prepared in the Han dynasty by astrologers as a regular 

 part of social life, especially when marriages were about to be 

 solemnized. Some of the old astronomical circles are preserved 

 in the new geomantic chart. This was the compass used when 

 Shen kwa wrote on the south-pointing needle in the eleventh 

 century. This author mentions that any iron needle acquires po- 

 larity by rubbing it on a piece of loadstone. He alludes to the 

 variation as a fact which he himself had observed, and speaks of 

 the south-pointing needle as an implement used by the professors 

 of geomancy. By them it was employed in the form of a float 

 upon water. After this, in 1122, an ambassador to Corea de- 

 scribes the use of the floating needle on board ship while he made 

 the voyage. This is the first instance, the earliest by more than 

 a century, of the use of the mariner's compass on board ship, 



found as yet in any book, native or foreign. The existence of 

 the book in which this is recorded settles the question of the first 

 use of the mariner's compass at sea in favor of the Chinese. At 

 that time the needle floated on water supported on a piece of wood, 

 but in the Ming dynasty some Japanese junks engaged in piracy 

 were captured by the Chinese, and the compass in use on board 

 was found to have the needle dry and raised on a pivot, while 

 still pointing southward. The Japanese had learned from the 

 Portuguese navigators to make a compass of this kind, and proba- 

 bly the needles they used were brought from Europe. From this 

 time, the Chinese adopted the principle of a pivot, and made their 

 compasses without a well of water in the middle to float the nee- 

 dle in. Charts were probably used of a very rough kind, but how 

 far is not known. What is known is that the junk-master was 

 aware of the direction in which the needle must point to reach 

 the port to which he was going. In the Sung dynasty, embracing 

 part of the tenth, as well as the eleventh, twelfth, and part of the 

 thirteenth centuries, Chinese junks went to Persia and India. 

 The Arabs trading to China directly would learn at that time the 

 use of the compass, and would apply it on board their dhows. 

 From them the Europeans learned this useful invention. 



The credit of the discovery, both of the polarity of a magnetized 

 needle and its suitability for use by mariners at sea, must, there- 

 fore, according to the writer, be given to the Chinese, says Nature, 

 in commenting on the article. It is China also that has the credit 

 of having first noticed that any iron needle may be polarized by 

 rubbing it with a magnet. In the thirteenth century the Arabs ■ 

 used a floating compass on their dhows. The needle was made to 

 float on the water by attaching it crosswise to a cornstick or 

 splinter of wood. A magnet applied to it drew it into a north 

 and south direction. They would use Western notation to naark 

 the quarters and intermediate points on the horizon. When, 

 therefore, the mariner's compass was adopted from them, the 

 Chinese 24 points were not communicated. In the European 

 compass the notation of 32 points is Western, and rests on the 

 winds and the sun. In the Chinese primitive mariner's compass 

 the notation is that of the professors of geomancy, and rests on 

 the old astrological division of the horizon into twelve double 

 hours. From the Arab account we learn, what the Chinese ac- 

 counts do not tell us, that the Chinese floated the needle by in- 

 serting it in a splinter of wood. 



LETTERS TO THE EDITOR. 



#** Correspondents are requested to be as brief as possible. The loriter^s navie 

 is in all cases required as proof of good faith. 



On request in advance, one hundred copies of the number containing his 

 communication will be furnished free to any correspondent. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



Crime among Washington Negroes. 



A CONTRIBUTOR to the Washington Evening Star of the 5th 

 instant, signing himself "A Friend of the Negro," has recently 

 been making some comparative studies of the records of the 

 Washington police courts, and greatly deplores the showing for 

 crime they exhibit against the rising generation of Washington 

 negroes. He states, and there is every reason to believe that bis 

 statement is true, that "the police report for the year ending 

 June 25. 1890, shows as follows : assaults on policemen, 163, by. 

 whites 75, by colored 87; assaults on special ofiicers, 25, by whites 

 9, by colored 16. Last year three policemen were killed by ne- 

 groes, two when attempting to arrest them, and there is scarcely 

 a year that this does not occur. In the Star of Dec. 24, 1888, it 

 was stated that there were then in jail, awaiting trial or sentence 

 for murder, 16 persons, 2 white and 14 colored. In the Post of 

 March 26, 1890, it was stated that there were then on the calendar 

 18 murder trials, and in the Star of Dec. 39, 1888, it was stated 

 that there had been in the District during the year 26 murders, 

 the greater portion of which was by negroes. Now, when it is 

 borne in mind that they constitute but one-third of the population, 

 it will be seen that this is a terrible record." 



Investigating this matter still further, the Star correspondent is 

 enlightened in other directions, for he soon finds out that it is the 

 present generation of negroes that is responsible for the majority 



