How Was Edmond Halley’s Map of Magnetic Declination (1701) Constructed?

Edmond Halley made two scientific voyages in the Atlantic Ocean as captain of the HMS Paramore between 1698 and 1700. Following these voyages he published the first map showing lines of equal magnetic declination in 1701. Halley did not reveal how he constructed the map, however, and it remains unknown. In this study, a construction procedure is hypothesized that uses mathematical tools that were available in his day, namely arithmetical averages and Isaac Newton’s method of divided difference for fitting a polynomial curve to data. To enable his map construction, a method is suggested whereby Halley could have created new data to augment the situations where insufficient data were collected.     

基于磁化率测量平遥古城古砖的烧制温度

古砖的烧制温度决定了其物理力学性质。本研究提出基于磁化率来确定古砖烧制温度的方法。通过对古砖重新加温,测量不同温度下古砖的磁化率,得到磁化率差值的平方-温度曲线图。图中第一个较大的偏差对应的横坐标即为古砖的烧制温度。利用上述方法测得实际烧制温度为700℃、800℃和900℃的黏土砖的烧制温度分别为690℃、810℃和870℃。二者误差较小,认为利用该方法确定砖的烧制温度可行。本研究利用该方法确定了平遥古城10块古砖的烧制温度,发现其烧制温度在650～690℃和850～870℃两个区间范围内。据此推测平遥古城古砖是以秸秆和木柴为燃料烧制而成。本研究实验结果可为古建筑修复和保护提供理论参考。     

A Sixteenth-Century Draft Plan of Lisbon’s Western Suburb

The National Library of Brazil has in its cartographic collection a little-known late sixteenth-century ichnographic plan of Lisbon, Portugal, showing the city’s western extramural suburb. In this article the unfinished draft plan is analysed for what it reveals of the mapmakers’ surveying methods. Comparison of the plan with other historical sources suggests that it was produced by Giovanni Vincenzo Casale and Alexandre Massai for military purposes between 1590 and 1597. This makes it the oldest ichnographic plan of Lisbon known to date, replacing the better known ichnographic plan of Lisbon signed by João Nunes Tinoco in 1650.     

Images of buried graves in Bayat,Afyon (Turkey) from high-resolution magnetic data and their comparison with preliminary excavations

Dedemezari necropolis, the site of our study, is located in the west of Turkey near Afyon. Archaeologists think that it belongs to the Middle Bronze age. A high-resolution magnetic survey identified buried material highly accurately. In particular, anomalies, which are transformed by the analytic signal method, clarify the observed magnetic anomalies. Magnetic surveying was applied in three different areas in this study. The map of analytic signal-transformed anomalies presented good results on preliminary excavation in trenches A and B. Two types of graves are found in the study area. One is made of clay and the second is carved in the rocks. Shapes of the buried graves are mainly cylindrical and elliptical. Most of the magnetic anomalies are elliptical and reflect the shape of the buried materials. Future excavations in Dedemezari necropolis will be able to be carried out more easily due to the known locations of the buried graves.     

地面核磁共振方法在石质文物保护中的应用

石质文物破坏问题不仅在于人为破坏和表面污染,更多来自自然因素对文物的破坏,例如,日晒雨淋、风沙吹蚀、地表水的冲刷、地震、地下水的侵蚀溶蚀。为对第六批全国重点文物保护单位阳华岩摩崖石刻露天石质文物病害进行探查,采用无损探测的地面核磁共振方法和探地雷达方法,直接找水的地面核磁共振方法成功探测出摩崖石刻依附岩体地层含水分布状况。探地雷达方法探测出依附岩山体内岩溶、裂隙的发育状况。两种方法探测结果发现,石刻依附岩体内岩溶、裂隙发育,部分区域岩溶裂隙带已成为地下水汇聚场所或流通通道,对阳华岩摩崖石刻构成了极为严峻的侵蚀威胁。两种方法解释结果互为验证,研究结果为阳华岩摩崖石刻的病害治理和保护提供了宝贵的基础资料。