Page:Popular Science Monthly Volume 44.djvu/441

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��general taxation, are the imposition of tolls, which has now been generally abandoned, and recoupment, or buying the property be- fore the improvement is made as in the opening of new streets and public places and reselling it afterward, which involves a large outlay of capital, and runs counter to the generally existing constitutional provi- sions respecting the exercise of eminent do- main. For young and growing municipali- ties the method of special assessment is considered the best. " With few excep- tions and abuses, it has been operated in the United States to the general satisfaction of all. It rests upon principles of right and justice. It brings quick results at the very time when needed. It discourages the speculative holding of unimproved urban property."

Charaeteristics of Lunar Craters. In

the study of lunar physiography or physiog- nomy, says Prof. G. K. Gilbert, interest nat- urally centers in the craters, for these are the dominant features. All theories begin with them. Their range in size is great, extend- ing from a maximum of about eight hundred miles in diameter to a minimum of less than one mile. The size of the smallest ones is not known, as they are beyond the present power of the telescope. Within this range are several varieties, more or less correlated in size, but their intergradation is so per- fect that they are all regarded as phases of a single type. To describe them one should picture to himself a circular plain, ten, twenty, fifty, or one hundred miles in diameter, sur- rounded by an acclivity which everywhere rises steeply but irregularly to a rude ter- race, above which is a circular clifP likewise facing inward toward the plain. This cliff is the inner face of a rugged, compound, an- nular ridge, composed of shorter ridges which overlap one another, but all trend con- centrically. Seen from above, this ridge calls to mind a wi-eath, and it has been so named. From the outer edge of the wreath a gentle slope descends in all directions to the general surface of the moon, which it is convenient here to call the outer plain. The outer slope of tlie crater may be identical in surface character with the outer plain, or it may be radially and somewhat delicately ridged as though by streams of lava. The

��inner slope from the base of the clifE to the margin of the inner plain is broken by uneven and discontinuous terraces. From the center of the inner plain rises a hill or mountain, sometimes symmetric but usually irregular and crowned by several peaks. From the outer plain to the base of the wreath the ascent is one thousand to two thousand feet, and the ascent thence to the top of the wreath may be as much more. The descent from the wreath to the inner plain is ordi- narily from five thousand to ten thousand feet, and the height of the central hill is from one thousand to five thousand feet. With rare exceptions the inner plain is sev- eral thousand feet lower than the outer plain. The central hill is not universally present, but appears in rather more than half the craters of medium size, and tends to disappear as the craters become larger. Mr. Gilbert attempts to account for the origin of these craters by collisions of meteoric bodies with the moon, or of the moonlets by the aggregation of which under the meteoric theory the moon has been formed, and is supported by the fact that the splash produced by dropping a pebble into pasty mud, etc., has the form of a crater.

The Royal Cinnamon of Tonkin. The

cinnamon of Thanh-Hoa, Tonkin, called roy- al cinnamon, is highly esteemed by the An- namites, and great value is attached to pieces of its bark as presents. It is not cultivated, but grows in thick, hardly acces- sible forests on the Muong Mountains, where some cantons are tributary to Annam. Each canton must furnish the king a tribute of three stools of cinnamon a year. When an inhabitant learns of a stool, he immediately informs the mayor of his village ; the mayor informs the sub-prefect, and he advises the governor of the province of the fact, who makes report of the matter to the court. The Quang phu, or sub-prefect, sends a squad of men to guard the tree, who are not relieved till the crop is gathered, in the presence of the Quang phu or of some man- darin deputized by him. The whole crop is supposed to go to the king, but the olEcers know how to retain a little of it. So pre- cious a spice as is this particular kind has not entered into commerce, and so jealously is it guarded that it is extremely difiicult to

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