登陆注册
5302100000012

第12章 BOOK I.(11)

"During the second decade of the twentieth century the engineers decided to try the plan of running half of a transatlantic liner's screws by electricity generated by the engines for driving the others while the ship was in port,this having been a success already on a smaller scale.For a time this plan gave great satisfaction,since it diminished the amount of coal to be carried and the consequent change of displacement at sea,and enabled the ship to be worked with a smaller number of men.The batteries could also,of course,be distributed along the entire length,and placed where space was least valuable.

"The construction of such huge vessels called for much governmental river and harbour dredging,and a ship drawing thirty-five feet can now enter New York at any state of the tide.

For ocean bars,the old system of taking the material out to sea and discharging it still survives,though a jet of water from force-pumps directed against the obstruction is also often employed with quick results.For river work we have discovered a better method.All the mud is run back,sometimes over a mile from the river bank,where it is used as a fertilizer,by means of wire railways strung from poles.These wire cables combine in themselves the functions of trolley wire and steel rail,and carry the suspended cars,which empty themselves and return around the loop for another load.Often the removed material entirely fills small,saucer-shaped valleys or low places,in which case it cannot wash back.This improvement has ended the necessity of building jetties.

"The next improvement in sea travelling was the 'marine spider.'

As the name shows,this is built on the principle of an insect.

It is well known that a body can be carried over the water much faster than through it.With this in mind,builders at first constructed light framework decks on large water-tight wheels or drums,having paddles on their circumferences to provide a hold on the water.These they caused to revolve by means of machinery on the deck,but soon found that the resistance offered to the barrel wheels themselves was too great.They therefore made them more like centipeds with large,bell-shaped feet,connected with a superstructural deck by ankle-jointed pipes,through which,when necessary,a pressure of air can be forced down upon the enclosed surface of water.Ordinarily,however,they go at great speed without this,the weight of the water displaced by the bell feet being as great as that resting upon them.Thus they swing along like a pacing horse,except that there are four rows of feet instead of two,each foot being taken out of the water as it is swung forward,the first and fourth and second and third rows being worked together.Although,on account of their size,which covers several acres,they can go in any water,they give the best results on Mediterraneans and lakes that are free from ocean rollers,and,under favourable conditions,make better speed than the nineteenth-century express trains,and,of course,going straight as the crow flies,and without stopping,they reach a destination in considerably shorter time.

Some passengers and express packages still cross the Atlantic on 'spiders,'but most of these light cargoes go in a far pleasanter and more rapid way.The deep-displacement vessels,for heavy freight,make little better speed than was made by the same class a hundred years ago.But they are also run entirely by electricity,largely supplied by wind,and by the tide turning their motors,which become dynamos while at anchor in any stream.

They therefore need no bulky boilers,engines,sails,or coal-bunkers,and consequently can carry unprecedentedly large cargoes with comparatively small crews.The officers on the bridge and the men in the crow's nest--the way to which is by a ladder INSIDE the mast,to protect the climber from the weather--are about all that is needed;while disablement is made practically impossible,by having four screws,each with its own set of automatically lubricating motors.

"This change,like other labour-saving appliances,at first resulted in laying off a good many men,the least satisfactory being the first to go;but the increase in business was so great that the intelligent men were soon reemployed as officers at higher rates of pay and more interesting work than before,while they as consumers were benefited as much as any one else by the decreased cost of production and transportation.

"With a view to facilitating interchange still further,our Government has gradually completed the double coast-line that Nature gave us in part.This was done by connecting islands separated from shore by navigable water,and leaving openings for ingress and exit but a few hundred yards wide.The breakwaters required to do this were built with cribbing of incorrodible metal,affixed to deeply driven metallic piles,and filled with stones along coasts where they were found in abundance or excess.

This,while clearing many fields and improving them for cultivation,provided just the needed material;since irregular stones bind together firmly,and,while also insoluble,combine considerable bulk with weight.South of Hatteras,where stones are scarce,the sand dredged from parts of the channel was filled into the crib,the surface of which has a concave metallic cover,a trough of still water being often the best barrier against the passage of waves.This double coast-line has been a great benefit,and propelled vessels of moderate draught can range in smooth water,carrying very full loads,from Labrador to the Orinoco.The exits are,of course,protected by a line of cribbing a few hundred feet to seaward.

同类推荐
  • 弥勒上生经宗要

    弥勒上生经宗要

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 佛入涅槃密迹金刚力士哀恋经

    佛入涅槃密迹金刚力士哀恋经

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • Sky Pilot

    Sky Pilot

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 帝京景物略

    帝京景物略

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 文穆念禅师语录

    文穆念禅师语录

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
热门推荐
  • 草原猛士的旅程

    草原猛士的旅程

    广袤无垠的草原,气候类型多样,植物种类丰富,植被类型复杂。在如此辽阔的草原上还生活着许多可爱的野生动物。但是由于人类对草原不合理地开发利用,导致草原生态环境恶化,影响了草原的可持续发展,危机人类与动物的生存环境。如何保护草原、保护地球生态环境,成为人类面对的课题。
  • 如果我变成回忆

    如果我变成回忆

    余暮烟爱了陆临川十年,卑微到尘埃里,却未开出花来。直到她死的那一刻,陆临川才发现,原来失去她,多活一秒都是煎熬……--情节虚构,请勿模仿
  • 珥笔肯綮

    珥笔肯綮

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 神禁纹

    神禁纹

    因为身体的不适,竟没想到是意外的收获,让他踏上了不平凡的路程!
  • 冰湖上的盗鱼贼

    冰湖上的盗鱼贼

    前些日子,王队长派张凤祥领我和二愣子回渔村运回来几张大拉网。想不到,我们返回朱老四大泡子途中在黑林子迷路了不说,过夜时还遭遇狼群攻击,在黑林子坚持三天四夜,终于跟前来寻找我们的王队长他们会合了,把大拉网运到目的地。但朱老四大泡子水面实在空旷,最后拉网小队不得不放弃了,转移到卧牛河上游的东大泡子打拉网。西北风裹挟着雪粉在旷野中不停地呼啸刮过,十几个渔民沿着轧硬的爬犁印,迎着初升的太阳向下一个捕鱼点走去。这些日子,我们一直在卧牛河上游的东大泡子打拉网。
  • 皎皎明月问君孤兮

    皎皎明月问君孤兮

    苏月笙小姐,,一位手机控,在某一天突然就死了。最后穿越了。不明不白(哭笑)后来,借着自己在得来的权限~她手机。在古代兴风作浪。结果还没开始浪就出来个美男对自己一见钟情。诶呀呀好开心!!
  • 绝代之公主:暗夜美男团

    绝代之公主:暗夜美男团

    她高雅温柔,她冷漠纯真,她精灵甜美。公主们的童话故事,她们舞动奇迹,她们创造属于自己的传奇,她们经历了坎坷,磨难,但始终不变的是她们的友谊。她们本以为,可以这样单纯快乐下去,但,突如其来的意外终结了她的性命,手中洋溢幸福的四叶草变成三叶草,幸福,是不是远离了呢?一直等到恶魔王子,天使骑士们的来到,绝世公主的幸福,又延续下去了……这是一场属于三位公主的独一无二的童话。
  • 天香

    天香

    从百年名门琅琊王氏贵女,到湘东王府女官章要儿,她与他,相隔万千杀孽,却两心相惜。情天恨海,繁华流光,她因爱而放弃仇恨,却在层层阴谋中永失所爱。乱世桃花逐水流,这一世的波折坎坷,就成她传奇的一生。她终成南陈皇后,主宰三代帝王更迭,天下兴衰。而她用尽毕生心血所调制的御天香,亦在她之后缥缈消散于九州天地之间。
  • 契约丑妻:帅老公别跑

    契约丑妻:帅老公别跑

    “只要你娶了这个丑女人,我保证马上资金注入你们孙氏避免破产的危险。”白富美的前女友趾高气扬并带着戏谑的在孙建安面前笑道。“娶就娶,但你要说话算话!”高富帅的孙建安牛脾气上来了,“不就是一个契约丑妻吗?晚上关上灯你和她都一样。”前女友听到这里脸都气绿了,“好,我就要看看你每天都面对着一个丑女丑妻要怎么生活的幸福又有滋味~!”<br/>??“尼玛,你们说谁丑呢?我只不过就是单眼皮厚嘴唇和趴鼻梁,又壮了点而已。嘿嘿,不过这男人可真帅,天上居然砸下了个帅老公给我,不要白不要。”刘双喜对着孙建安直流口水。<br/>
  • 年轻人必知的心理调节书

    年轻人必知的心理调节书

    每个人的心理都有巨大的潜能,通过合理调节,聚集能量就能超水平的发挥出来,从而成就自己的智慧和人生。《年轻人必知的心理调节书》正是打开他人心理之门的钥匙,熟读本书,能够使我们在最短的时间内获取他人的心理密码,从而能够在与不同性格的人交往时运用恰当的方式,能够在第一时间学会察言观色,见机行事。