156 



SCIENCE. 



[Vol. XV. No. 370 



shape, the ground is covered with a layer of loose sand a few 

 inches in thickness, to form a more perfect bed for the boards 

 to rest upon, and to keep the boards from contact with the 

 earth beneath, so as to form a sub-drainage against the effects 

 of freezing weather. The sand is struck off to a perfect surface 

 by a templet made to suit the desired curve, and guided by 

 slats set to grade stakes. 



The boards to be used need not be more than one inch in 

 thickness, and ought not to be less than ten inches in width. 

 The best timber for the purpose is that least subject to rot 

 under the circumstances. Good white oak has been used suc- 

 cessfully. The boards should be dipped in hot coal-tar or other 

 preserving material. They are then carefully laid upon the 

 sand-bed — lengthwise with the street would be the most 

 convenient way — from curb to curb, with a regular curve all 

 the way. No gutters are necessary, except such as are formed 

 by the crown of the pavement. The broad surfaces of the 

 boards bridge over all minor irregularities of the grading, and 

 widely distribute all weights or pressure; and the floor forms 

 a complete and perfect foundation for the hard material to fol- 

 low. It is best to cover the boards with a layer of loose sand 

 an inch or two in thickness, to form a more perfect bed for the 

 bricks, which can be struck off with the templet, as before 

 described. 



The hard-barned bricks are next laid down. If they are of 

 the ordinary shape of building-bricks in common use, they 

 should be placed on edge, and laid "herring-bone" style, by 



blocks, and in most places for less than well-laid wooden 

 blocks, or even good macadam roadways. It is controlled by 

 the Hale Pavement Company of Staunton, Va. 



MAJOR POWELL' S ADDRESS TO THE MINING ENGINEERS, i 

 Mr. Peesident, and Members of the Institute of Mining 

 Engineers, — It is with great pleasure that I greet you, and wel- 

 come you to Washington. The people of the United States ob- 

 tain vast values from the rocks. The sum of the annual products 

 of the mines of the United States is now more than six hundred 

 millions of dollars. Over this production you preside. It is by 

 your genius and skill that these industries are prosecuted. These 

 affairs, which are confided to your guidance are not only great in 

 themselves, but they constitute an integral part of all of the in- 

 dusti-ies of the land, as they are all profoundly interdependent. 

 The industries of manufacture, transportation, agriculture, and 

 exchange have their interests, their prosperity, and their value 

 to the people at large, all interwoven with the industry of min- 

 ing, for the success and prosperity of which you are responsible. 

 Deep in the mountains lie the values which you seek ; buried 

 under the hills are the substances which you bring to light ; con- 

 cealed beneath the valleys are the materials which you resurrect. 

 By your insight they are discovered. The prosperity of the land 

 depends upon your knowledge of the structure of the earth and 

 the secrets which lie buried in the depths of the rocks. By your 

 knowledge and mastery over the powers of nature, all these sub- 



THE HALE PAVING SYSTEM. 



which means all joints in the board floor are straddled. The 

 ■seams are then filled with sand, and the bricks settled in th eir 

 beds with a flatter, well rammed, or rolled with 'a heavy 

 roller. 



In cities having very heavy traffic to follow immediately the 

 laying of the pavement, it is sometimes preferred, after the 

 interstices between the bricks are half filled with fine sand, 

 to complete the filling with hot pitch made by boiling gas-tar 

 until the more volatile portions are driven off. This, when 

 it cools, makes the pavement at once impervious to water, 

 cements the bricks together, and helps to hold them firmly in 

 place. This is generally advisable wherever clean fine sand 

 cannot be obtained to fill the interstices. 



A perceptible elasticity tends to favor the bricks when sub- 

 jected to a crushing weight. The bricks being in place, their 

 flat surfaces agreeing with each other and with the flat surface 

 of the boards beneath, the bearings are perfect and equal : they 

 ■can be broken only with difficulty, and cannot get out of place; 

 and if at any tims it is desired to lay pipes or sewers beneath 

 the pavement, the materials, being all disconnected, can be 

 rapidly taken up and laid aside, and as rapidly replaced at 

 small expense, no new materials being required, and no patch- 

 ing to be done, every thing fitting in its place. 



The durability of this pavement has been tested by several 

 years of hard service in the streets of Charleston, W. Va., and 

 in other places. The cost of this pavement in any given locality 

 depsnds upon the cost of sand, oak or other durable boards, 

 hard-burned brick, gas-tar, and labor at such locality ; but it is 

 claimed that it can be laid in any city or town in the United 

 States, having length of streets sufficient to warrant the under- 

 taking, for very much less than asphalt or Belgian granite 



stances are wrested from the adamantine grasp of mountain, hill, 

 and valley, and placed in the possession of mankind. By your 

 knowledge of the constitution of the rocks, and the various pro- 

 cesses by which they may be transformed, these substances, so 

 useful to mankind in the industries of civilization, are extracted, 

 and transmuted into forms ready for the use of the people. But 

 for your agency, the factory-wheels of the land would stop, the 

 life of transportation would expire, the valleys of agriculture 

 would be reforested, and the marts of exchange, now ti'odden by 

 busy feet, would be clothed by a mantle of desolation. 



That labor may be successful, that the ever-increasing wants 

 of ever-increasing men may be supplied, labor must have guid- 

 ance. In the centuries that have passed, tyrants have directed 

 laborers as slaves, or held them under conti'ol as abject servants 

 of want ; but under modem culture the laborer is emancipated 

 from slavery supported by chains and whip, and the slavery sup- 

 ported by want and dependence. Muscles of brawn are no longer 

 shackled ; but by your transcendent genius the powers that gleam 

 from the sun upon the world, the powers that flow in gTeat rivers, 

 the powers that are concealed in banks of coal, filling the hills 

 and mountains, the powers that lurk in the chemical re-actions 

 of the rocks that constitute the ci-ust of the earth, — all these 

 powers are enslaved, all these powers are shackled, all these 

 powers are made the sei-vants of mankind. The crack of the 

 lash is superseded by the glint of thought. The modem rulers 

 are the men who control the powers of nature. 



It is thus that the members of the American Institute of Min- 

 ing Engineers constitute the greatest body of rulers now on the 

 globe. When we consider the power that is wielded as a boon to 

 mankind, there is no other parliament or congress whose delib- 

 1 Delivered in Washington, D.C., Feb. 19. 



