CHAPTER XIII. CRANES.

It appears that Mr. Stevenson was much perplexed¹ as to what sort of cranes he should use in building the Bell Rock Lighthouse. His difficulties were twofold:—

First, In consequence of the dovetailed form of the stones he required a crane that would drop them as nearly as possible on the beds on which they were permanently² to rest.

Second, Supposing he devised a guy crane that overcame this difficulty, what was to be done as the building rose in height, and the guys became too nearly perpendicular³ to admit of such a crane being used?

In his private notes Mr. Stevenson regrets that he could get no advice from anybody he consulted, all of whom recommended him to employ common sheer poles, such as had been used by Smeaton at the Eddystone; and he adds, “I may say, morning, noon, and night, these difficulties have haunted me.” But thrown back on his own resources, and appreciating the difficulty as no one else could so well do, he found, as is often the case, that he was his own best counsellor, and he succeeded in solving the problem that had given him so much concern, by inventing what he called the “moveable beam182 crane,” and also the “balance crane,” which are shown in Plate XI. The former, as modified to suit particular cases, is now in universal use for building purposes, and the latter has been employed in rearing most of our Rock Lighthouses, so that I think professional readers will not object to my giving Mr. Stevenson’s description of these cranes, as designed by him at the beginning of this century. He says:—

“In cranes of the common construction the beam is a fixture⁴, and is placed at right angles to the upright shaft⁵: but in the machine represented in the Plate (Fig. XI-1), its attachment⁶ is at the lower extremity⁷ of the crane, where it is moveable up and down upon a journal or bolt. This crane is therefore termed a moveable beam crane. The moveable property of the beam, in so far as the writer knows, is new, and possesses the advantage of laying any stone within its range perpendicularly⁸ on its site. This, from the dovetailed form of the stones at the Bell Rock, rendered it particularly fitted for this work, to which a crane of the ordinary construction could hardly be said to be applicable. At the Eddystone Lighthouse this operation was performed by means of triangular⁹ sheers; but, from the greater extent of the Bell Rock works, and their greater depth in the water, such means must have rendered the process of building extremely tedious. These cranes were necessarily immersed at high water, and were retained in their places by four guys fixed¹⁰ at the top of the upright shaft, and the moveable jib or beam being lowered down, was secured to an eyebolt batted into the rock.”

PLATE XI.

MOVEABLE JIB and BALANCE CRANES.

W. & A. K. Johnston, Edinburgh.

183

“The ‘balance crane’ (Fig. XI-2) was constructed on a new principle for building the upper part of the Bell Rock Lighthouse, when the guy ropes of the moveable beam crane became ‘too taut,’ as sailors express it, or were too near the perpendicular, thereby¹¹ rendering¹² the beam cranes unstable¹³. To remedy this, the balance crane was so arranged as to be kept in equilibrium¹⁴ by a back weight of cast iron, so adapted as to counteract¹⁵ the varying load upon the working arm or beam. The elevation¹⁶ here represented is the same in principle with that used at the Bell Rock, but differs somewhat in form, agreeably to improvements made in order to adapt it to the erection of the Carr Rock Beacon¹⁷. The upright central column is a tube of cast iron put together in convenient lengths with flush joints¹⁸, after the manner of spigot and faucet¹⁹, fitted by turning and boring. The centre column of this machine might have been carried to any suitable or convenient height, by adding length to length, as the building advanced, without once moving the foot on which it rested, but at the Bell Rock not more than three lengths of from six to nine feet were generally in use. A malleable²⁰ iron cross head was stepped into the void of the central shaft or column when the body of the crane was to be elevated. This operation was accomplished²¹ simply by hooking the main ‘purchase’ and ‘traveller’ chains into the eyes of the crosshead, when the machinery²² of the crane was employed with great facility as a locomotive power for lifting itself as each new length of central column was added. The weight of this crane as used at the Carr Rock did not exceed two tons.”

1 perplexed   

adj.不知所措的

参考例句：

• The farmer felt the cow,went away,returned,sorely perplexed,always afraid of being cheated.那农民摸摸那头牛，走了又回来，犹豫不决，总怕上当受骗。
• The child was perplexed by the intricate plot of the story.这孩子被那头绪纷繁的故事弄得迷惑不解。

2 permanently   

adv.永恒地，永久地，固定不变地

参考例句：

• The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
• The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。

3 perpendicular   

adj.垂直的，直立的；n.垂直线，垂直的位置

参考例句：

• The two lines of bones are set perpendicular to one another.这两排骨头相互垂直。
• The wall is out of the perpendicular.这墙有些倾斜。

4 fixture   

n.固定设备；预定日期；比赛时间；定期存款

参考例句：

• Lighting fixture must be installed at once.必须立即安装照明设备。
• The cordless kettle may now be a fixture in most kitchens.无绳电热水壶现在可能是多数厨房的固定设备。

5 shaft   

n.(工具的)柄，杆状物

参考例句：

• He was wounded by a shaft.他被箭击中受伤。
• This is the shaft of a steam engine.这是一个蒸汽机主轴。

6 attachment   

n.附属物，附件；依恋；依附

参考例句：

• She has a great attachment to her sister.她十分依恋她的姐姐。
• She's on attachment to the Ministry of Defense.她现在隶属于国防部。

7 extremity   

n.末端，尽头；尽力；终极；极度

参考例句：

• I hope you will help them in their extremity.我希望你能帮助在穷途末路的他们。
• What shall we do in this extremity?在这种极其困难的情况下我们该怎么办呢？

8 perpendicularly   

adv. 垂直地, 笔直地, 纵向地

参考例句：

• Fray's forehead was wrinkled both perpendicularly and crosswise. 弗雷的前额上纹路纵横。
• Automatic resquaring feature insures nozzle is perpendicularly to the part being cut. 自动垂直功能，可以确保刀头回到与工件完全垂直的位置去切割。

9 triangular   

adj.三角（形）的，三者间的

参考例句：

• It's more or less triangular plot of land.这块地略成三角形。
• One particular triangular relationship became the model of Simone's first novel.一段特殊的三角关系成了西蒙娜第一本小说的原型。

10 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

11 thereby   

adv.因此，从而

参考例句：

• I have never been to that city,,ereby I don't know much about it.我从未去过那座城市，因此对它不怎么熟悉。
• He became a British citizen,thereby gaining the right to vote.他成了英国公民，因而得到了投票权。

12 rendering   

n.表现，描写

参考例句：

• She gave a splendid rendering of Beethoven's piano sonata.她精彩地演奏了贝多芬的钢琴奏鸣曲。
• His narrative is a super rendering of dialect speech and idiom.他的叙述是方言和土语最成功的运用。

13 unstable   

adj.不稳定的，易变的

参考例句：

• This bookcase is too unstable to hold so many books.这书橱很不结实，装不了这么多书。
• The patient's condition was unstable.那患者的病情不稳定。

14 equilibrium   

n.平衡，均衡，相称，均势，平静

参考例句：

• Change in the world around us disturbs our inner equilibrium.我们周围世界的变化扰乱了我们内心的平静。
• This is best expressed in the form of an equilibrium constant.这最好用平衡常数的形式来表示。

15 counteract   

vt.对…起反作用，对抗，抵消

参考例句：

• The doctor gave him some medicine to counteract the effect of the poison.医生给他些药解毒。
• Our work calls for mutual support.We shouldn't counteract each other's efforts.工作要互相支持，不要互相拆台。

16 elevation   

n.高度；海拔；高地；上升；提高

参考例句：

• The house is at an elevation of 2,000 metres.那幢房子位于海拔两千米的高处。
• His elevation to the position of General Manager was announced yesterday.昨天宣布他晋升总经理职位。

17 beacon   

n.烽火，（警告用的）闪火灯，灯塔

参考例句：

• The blink of beacon could be seen for miles.灯塔的光亮在数英里之外都能看见。
• The only light over the deep black sea was the blink shone from the beacon.黑黢黢的海面上唯一的光明就只有灯塔上闪现的亮光了。

18 joints   

接头( joint的名词复数 )； 关节； 公共场所（尤指价格低廉的饮食和娱乐场所） （非正式）； 一块烤肉 （英式英语）

参考例句：

• Expansion joints of various kinds are fitted on gas mains. 各种各样的伸缩接头被安装在煤气的总管道上了。
• Expansion joints of various kinds are fitted on steam pipes. 各种各样的伸缩接头被安装在蒸气管道上了。

19 faucet   

n.水龙头

参考例句：

• The faucet has developed a drip.那个水龙头已经开始滴水了。
• She turned off the faucet and dried her hands.她关掉水龙头，把手擦干。

20 malleable   

adj.(金属)可锻的;有延展性的；(性格)可训练的

参考例句：

• Silver is the most malleable of all metals.银是延展性最好的金属。
• Scientists are finding that the adult human brain is far more malleable than they once thought.科学家发现成人大脑的可塑性远超过他们之前认识到的。

21 accomplished   

adj.有才艺的；有造诣的；达到了的

参考例句：

• Thanks to your help,we accomplished the task ahead of schedule.亏得你们帮忙,我们才提前完成了任务。
• Removal of excess heat is accomplished by means of a radiator.通过散热器完成多余热量的排出。

22 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。