1841.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



423 



almost finished the preceding year; and, in place of diffusing wealth, 

 we everywhere organize ruin. 



"The canal from the Marne to the Rhine, for example, has been 

 deplorably retarded. I am convinced, from a visit which I have just 

 made to the principal industrial establishment of the department of 

 the Meuse, of the disastrous consequences of this delay. I have seen 

 throughout that active and laborious country a true desolation reign- 

 ing. All the hopes which had been conceived of this grand and mag- 

 nificent communication vanish in the saddest disappointment, and each 

 contemplates with grief these immense works, created by an enormous 

 expenditure, which will be doubled by this fatal interruption. 



" It was in the session of 1S3S that the Chambers voted the opening 

 cf this canal, which is the admirable work of the engineer Brisson. 

 The Director-General of the Ponts-et-Chaiissks declared that eight 

 years at the most would be required to open this canal to the industry 

 of the country, and, in effect, from thatijeriod down to the commence- 

 ment of 1S41 we must accord to the Administration the justice of ad- 

 mitting that nothing was neglected which could expedite the prompt 

 completion of the work. So extraordinary was the activity which 

 was therein exhibited that it might have been fearlessly aflSrmed its 

 termination would not be later than 1846. Unfortunately, however, at 

 the commencement of the present year, the Administration ordered a 

 general slackening of the works, not only for the current year, but also 

 for those which are to follow. Nay, more, it has announced that the 

 credits allotted for the work in 1842 will be still less than those of 

 1841. It is easy to conceive the injurious effect of this determination, 

 as well upon the unfinished works as upon tlie industry of the depart- 

 ment of the Meuse, which reckoned upon the prompt execution of this 

 undertaking to rescue it from the crisis which it has undergone, and 

 which threaten now to become prolonged. It will be sufficient for me 

 to make known the state of the works in this department, with the 

 Slims necessary to urge them forward in 1S42, with a slight degree of 

 activity, and to acquaint the reader with the sums actually voted last 

 session. This information I have derived from the best possible 

 sources, including the engineers themselves, to whose zeal and skill I 

 cannot render too high a public homage. 



"Setting out from the limits of the department of the Meurthe, the 

 Marne-Rhine Canal is almost finished for a length of 17 kilometres 

 in the department of the Meuse. The prin'.-ipal work is the bridge- 

 canal on the river Meuse; this was commenced in November, 1840, 

 and all the arches are at this moment closed. To finish this portion 

 of the canal at the very most only the paltry sum of 300,000f. (12,000/.) 

 is requisite ; and this outlay would make it perfectly certain that in 

 the course of 1843 the canal would be opened to the industry of the 

 whole district, which would derive from it the greatest possible ad- 

 vantage. Well, this miserable sum it has been impossible up to this 

 day to obtain. 



•' The interval between the Ornain and the Meuse, which is that 

 portion of the canal where the works will be most tedious and expen- 

 sive, has been commenced throughout its entire length. Besides the 

 cuttings, which, according to the adjudications, amount to nearly 

 2,000,000f., this portion comprises the' tunnel at Mauvage, which will 

 be about 5,000 metres in length. The difficulties which arise, as well 

 from the nature of the ground as from the great quantity of water 

 whicli is met there, give every reason to apprehend that if the works 

 are not carried on with the utmost activity the expense, which has 

 been valued at 9,000,000f., will become doubled. From the Mauvage 

 tunnel to Vitry le Francais, where the canal effects its junction with 

 the lateral canal at the Marne, the want of money alone prevents the 

 immediate termination of the enterprise. What have the Chambers 

 voted for the Marne-Rhine Canal for the current year, and for 1842 ? 

 A sum of 3,000,000f., to be distributed amongst four departments. A 

 million will be probably allocated to the department of the Meuse, 

 which absolutely requires four. 



"The result will be, of course, an enormous loss to the state. To 

 finish tlie works twice the time must be employed, and perhaps twice 

 the capital. Inevitable injuries to all the portions that are not yet 

 finished, and indemnities to the contractors, who have engaged to ter- 

 minate within a given time the portions adjudged to eadi, and who, 

 having made all their preparations in consequence, have found them- 

 selves suddenly arrested in the execution of the works here, are the 

 first only and most obvious consequences of this ruinous system. 



" The point at which the most immense loss will be sustained by 

 tlie Government, if the works are not resumed with pristine vigour, i's 

 the Mauvage tunnel. In point of fact all the wells, to the number of 

 17, several of them 120 metres in depth, are alreadv pierced, and the 

 galleries are commenced. The tunnel is formed of potter's clay, which 

 easily becomes diluted in water. If the work is for a moment sus- 

 pended at the end of four or five days the whole will be inundated : 

 the wells and galleries will be filled with a liquid slime, and it will be 



more troublesome to repair what is done than it was to do it originally 

 Better never have commenced. And, yet so extraordinary wis the 

 activity at first displayed, that there was every reasonable expectation 

 of its being finished within three years, which would have caused a 

 saving of l,000,000f. But, with the miserable pittance accorded by 

 the Government to-day, no term can be foreseen either to the labour 

 or the expense. All must be arrested, all suspended. The payment 

 of the indemnities alone for the ground purchased will absorb the en- 

 tire credit. These, Sir, are facts of public notoriety which a great 

 number of persons engaged in manufacturing industry, agriculturists, 

 and good citizens, would have communicated to the Rlinister of Public 

 works, if, on his return from Alsace, he had visited, as we had gene- 

 rally hoped, this important portion of the Marne-Rhine Canal, But 

 these sad details will nevertheless reach him, and it is surely impossi- 

 ble that they could escape his patriotic solicitude. 



" It was easy to conceive that the ' eventualities' of war would lead 

 to such results. Men do not reckon up sacrifices when the honour of 

 the country requires them ; but that the already brimming measure 

 should still be filled to overflowing, when it is loudly proclaimed upon 

 all hands that there is no longer any danger for the peace of Europe — 

 this is what confounds and amazes every man of sense. What sort of 

 peace is that which nips every amelioration in the bud, and disarms 

 nothing but useful public works ?" 



To this powerful letter may be appended as a commentary the fol- 

 lowing paragraph from another portion of the same paper: — "So fre- 

 quent is the occurrence of accidents on every portion of the works 

 connected with the fortifications of Paris, that near each fort and de- 

 tached wall there have been established temporary hospitals, at which 

 surgeons are stationed from the different regiments employed at the 

 works." 



ON LEVELLING INSTRUMENTS. 



Sir — Having observed in the Journal of this month a description of 

 some improvements in Levelling Instruments, by Mr. T. Stevenson, 

 may I be allowed through the medium of your widely circulated 

 columns, to offer some observations on a subject which has engaged 

 much of my attention. 



The real practical value of Mr. Stevenson's improvements must 

 very much depend upon the purpose for which they were designed. 

 In some particular scientific researches, where the greatest nicety is 

 required, and time little or no object, I can conceive a vernier adjust- 

 ment both for the level and staff may be desirable. But for engineer- 

 ing purposes, as it is found that any slight errors in reading within 

 the Y^Ti of a foot, which is the usual grjduation of the staff, are not 

 carried on and increased, but eliminated or rather balanced, in any 

 series of observations, it is surely needless to seek greater accuracy in 

 the scale, at the expense of much additional time and labour. And in 

 fact, without regard to the tediousness of the operation, and the greater 

 liability of casual mistakes, the delicacy of a vernier reading must be 

 wholly lost and cancelled in practice, until we can command at alt 

 times a perfectly still atmosphere, and a true constant of refraction; 

 and even with these it will be necessary to provide ourselves with a 

 vernier adjustment for the spirit bubble — cross wires which are true 

 mathematical lines " without breadth" — materials on which heat and 

 moisture have no effect, and at the same time a rod, absolutely rigid, 

 and perfect in graduation, before we can insure the nicety here sought 

 for in the reading of the staff alone. 



The real chances of errof then in levelling operations consist, not 

 in the imperfection of the instruments so much as in our powers of 

 applying them — thus principally in the difficulty of securing at all 

 times a perpendicular line in a long staff, from the effects of the wind 

 or even its own weight in bending it, and at the same time the un- 

 steadiness of the holder in handling and turning it. The dependence, 

 indeed, under which he is placed to his staff-holder for correct results, 

 in spite of his utmost care and attention, must be painfully felt by 

 every accurate observer. To remedy, in part these uncertainties in 

 handling, I have lately had constructed, under my own observation, a 

 staff similar in graduation to those in general use, but differing in its 

 joints and fittings, the chief object having been to obtain a length of 

 rod tolerably unyielding, with a firm and immoveable basis. 



I regret that I am obliged to speak from description only, and there- 

 fore liable to mistake; but if I rightly understand Mr. S, the whole 

 length of his rod when extended is twice 12i, or 25 feet, and that this 

 is packed into a box 3i feet long by 4 inches square. Considerable 

 ingenuity must be displayed in this arrangement, and great conve- 

 nience obtained for travelling, but it does not say much for the 

 strength of the staff, and with so many joints as must be necessary, I 

 should consider that it could scarcely support its own weight in the 



