mis. I 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL, 



03 



ploying tliis force to draw lu.lts or catches to free tlie balls aiul allow tliem 

 to (irop ; a niimtier of ma^'iiets in cnmmutiication will develop tlieir furces at 

 distant stations at tlie same moment, and allow balls at several stations to 

 indicate tlie same second. 



4. Description of a Safelij- Wheel Jiini/- Revolver, to prevent Wheels of 

 Carriagen from flying off the Jiles. By Rev. Graham Mitchell, A.M. 



The ohjpct of this invention Is to prevent disasters, hy rendering it im- 

 possihle for any wheel fiyine off the axle, whether from tear and wear, or con- 

 cussion. Independently of all former contrivances of security for luiiiian 

 life, there is here superadded a Irass or iron ring attached to the wheel be- 

 hind the hush, which apart revolves along with the large wheel itself round 

 a nitch cut in the axle of the carriage, and which is designed to act ai a 

 preventive against a wheel ever Hying off, whatever be the velocity of levolu- 

 tion. 



INSTITUTION OF CIVIL ENGINEERS OF IRELAND. 



Dec. 14. — Col. II. D. JjNES, President, in the Chair. 



The following papers were read : — 



** Description of a Clock with a Ref/istering Machine attached." By Mr. 

 Sharp. — An ordinary cluck was exhibited, with the addition of a certain 

 number of projecting pins on the dial ; the interval between every two pins 

 expressed a certain portifni of time, being that which elapsed while the hour 

 hand of the chick, in its ordinary motion, passed from one pin to another; 

 a lever was attached to the liack of the diji, by means of which the hour 

 band ciiuhl be pushed in at any time against the face of the dial, and, by 

 coming in contact with one of the projecting pins imnediatelv under it, 

 push it in also, and the pin so puslied in woidd register, within but a few 

 minutes, the exact time the hand was brought in contact with the dial. Mr. 

 Sharp explained how, by means of a sufficient number of |)ins on the dial, 

 very small intervals of time might lie registered. This invention he con- 

 ceived could lie used for all the purposes of a noctuary, ami might, by 

 means of an additional mechanical contrivance, be made to register tlie 

 times of the arrival and departure of the traitis, by means of the trains 

 themselves. He also explained how the movement of the clock was not in 

 the least injured by this addition, and that this means of registering might 

 be also applied to clocks already constructed. 



*' -^ short account of the Fall dnnng a violent storm, of part of a Roof 

 in progress of erection over the Dublin terminus of the Midland Great 

 Western Railway." By Mr. Hemans. — The total length of the roof of this 

 building is 475 feet, and the width 120 feet, divided into two spans of 60 

 feet each, the roof resting on walls at either side, and on columns in the 

 centre. The centre columns are C2 ft. 6 in. apart, and are connected by flat 

 arches and gutter-plates. The whole structure, with the exception of the 

 columns, gutter-plates, tie-washers, and sockets, is composed of rolled iron. 

 The principal, wiiich are the only rafters, are 38 in number to each half-roof, 

 and are 12 ft. 6 in. apart. They are formed of what are called "deck 

 beams." The cover of the roof is of corrugated galvanised iron, and con- 

 nected by bolts and rivets similarly galvanised, and provision is made for 

 expansion and contraction. Twenty-five of the principals were erected on 

 each side, and the whole centre line of columns and arches complete, when 

 the storm, the cause of the accident, began. The principals not being con- 

 nected together by temporary diagonal braces (none would be required when 

 the corrugated covering was fixed), were exposed to the powerful action of 

 the gale in the direction in which no temporary provision had been made to 

 withstand latend pressure ; and the consequence was, as might naturally he 

 expected, that the greater portion of them were blown down one over the 

 other, like a pack of cards ; and the whole of them had snapped their 

 sockets. 



Several members expressed their satisfaction at Mr. Hemans having placed 

 on record this failure through inattention to the necessary precautions in the 

 execution, which would prove an useful lesson. 



" An account of the removal of a Mill at the Cults, near Coleraine." By 

 Col. H. D. Jones, President. — The paper was accompanied by several draw- 

 ings explanatory of the subject, and detailed the mode adopted for the re- 

 moval of a large mill, the height of which, to the eaves, was 05 feet, and 

 the walls were of proportionate thickness, being three feet at the level of 

 the ground story. The execution of the works in connection with the 

 drainage of Lough Neagh, rendered the removal of this mill necessary, and 

 the use of gunpowder was considered the most economical means of effect- 

 ing this object ; but the contiguity of the mill to several houses by the 

 roadside rendered it necessary to guard against accident, by limiting the 

 charge of powder. A detailed account was given of the quantity of powder 

 used, the mode of applying the charges, and the effect produced, and very 

 satisfactorily proved the economy of the measure. This work was conducted 

 under the superintendence of Mr. C. S. Ottley, the district engineer for 

 Lough Neagh drainage. — The President stated that he had used gunpowder 

 with much advantage, both as regarded effect and economy, in the removal 

 of large buildings, but especially in the removal of a large storehouse at 

 Flushans. 



Mr. M'Mahon stated the great advantage of adopting the plan which 

 had been so successfully tried in the present instance. 



Mr. Clarendon described the mode by which the hish dock wall bad 

 been removed at the site of the Dublin and Drogheda railway terminus in 



Amiens-street, which had been effected expeditiously and economically, and 

 without the use of cnnpowder. 



Mr. Dean called the attention of the Institution to the inctfioient state of 

 the sewerage of Dulilin. 



HINTS TO PLANTERS. 

 A correspondent of the Gardeners' Chronicle says, " In rambling throuL'h 

 the New Forest, I have been much struck by observing how much the beauty 

 of natural woods depends upon the open glades, or intervals hare of trees, 

 which there so frequently occur, and have often wondered why the land- 

 scape gardener so seldom imitates nature in this respect. In the disposition 

 of Ihe open and the woodrd spots, it may be observed that nature commonly 

 fills up the valleys with wood, and leaves most of the brows ami eminences 

 bare, and in an undulating country, nothing is more pleasing to the tye than 

 thus to see the woods creeping up the hollows and gradually feathering off, 

 and dis.ippearing as they approach the summits of the hills, which rise bare 

 of trees above them. The landscape gardener almost invaiiably does the 

 reverse. He commonly jdanls all the eminences (probably from the notion 

 of making a more conspicuous show at a distance), leaving his vacant spaces 

 in the valleys and lower grounds. By this means (putting appearance out 

 of the question) he subjects his trees to the doulile disadvantage of a more 

 exposed situation, and a shallower soil ; consequently his trees grow incom- 

 paratdy slower than they would do in the deeper soil and more sheltered 

 situation of the lower grounds. Trees differ so much in the soil and situa- 

 tion suitable to the different kinds, that it is of the utmost consequence to 

 the planter that the one should be adapted In the other; and if planters 

 could be induced to look after these thinirs themselves, instead of entrusting 

 them to the nurseryman, one would not so often see plantations fiUid with 

 such worthless trees as beech and sycamore, where more valuable sorts, such 

 as elm, ash. and cbesnut, would flourish equally well. With this view, I 

 have thrown together a few observations on the sorts of trees commonly 

 planted. The larch would, no doubt, be the most valuable tree that can be 

 planted, were it not unfortunately subject to that peculiar disease, called the 

 heart. rot, which, I believe, is not known to affect any other kind of tree. 

 After growing vigorously for twenty or more years, the heart of the tree up 

 to a considerable height becomes entirely rotten, without any apparent ex- 

 ternal decay. The cause of this singular disease is as yet unknown. I am 

 myself inclined to believe that it usually arises from too great dryness in the 

 soil. In Switzerland the native habitat of the larch is in situations abound- 

 ing in moisture, viz., the sides of slaty and granitic mountains ; and the 

 plantations in which, in this kingdom, it seems to flourish best, are in similar 

 situations in Scotland and Wales. In England it has principally been planted 

 on dry sandy heaths — a situation which affords tlie greatest contrast to its 

 native baliitat, and which the prevalence of the heart-rot shows to be uncon- 

 genial to its nature. In point of beauty little can be said in favour of the 

 larch ; it never forms a handsome mass of foliage ; and the spiky outline 

 even of the oldest woods always has a poo*", unpleasing effect. It must, 

 however, be acknowledged that a single tree of larch often has an elegant 

 appearance. The Scotch fir is of so hardy a nature that it will flourish in 

 almost any soil or situation. It is in very bad repute as a timber tree when 

 grown in England, which is a very singular fact, as it is well known that the 

 same species of pine, when grown in the north of Europe and the highlands 

 of Scotland produces Itiat excellent timber known as the red deal. Different 

 causes are assigned for this extraordinary difference in the timber grown in 

 England and grown abroad. Some persons suppose that the home and 

 foreign grown fir are different varieties of the same species, one of which 

 always produces hard and the other soft wood ; some suppose that the colder 

 climate and slower growth of the Baltic timber is the cause of its superiority ; 

 and any one who will take the trouble of counting the number of annual 

 lings in Baltic timber must see that its growth is in general excessively 

 slow; others consider that age alone is wanting to render the timber good, 

 and that if we were to allow English grown fir to attain the age of one or 

 two centuries, as is the case with the Baltic grown, our timber would be 

 equally valuable. That English fir timber does improve as ihe trees grow 

 older, is a fact well known to timber merchants ; and I can instance the roof 

 of the house in which I am now writing, which was framed of English fir, of 

 very large scantling, about forty years ago, and which to all appearance is 

 now as sound as the day it was put up. It must also be observed that Ihe 

 English fir is commonly cut down of small dimensions, and full of sap wood, 

 while most of the sap wood is cut away from the Baltic balks before we get 

 them. But there is still one point, which I have never seen noticed, which, 

 perhaps, may go far to account for the difference of quality. I mean the 

 season in which the timber is felled. It has never yet been ascertained that 

 resinous trees ought to be felled in winter, as is the universal practice in 

 England, and it is not unlikely that the resinous juices with which firs abound 

 in summer may tend to increase the durability of the timber felled in that 

 season. I would strongly impress on those who have the opportunity, how 

 desirable it would be to institute experiments on tkis point. It is stated, on 

 what appears to be good authority, that both in Norway and the rest of the 

 north of Europe fir trees are always felled in summer. In Switzerland, as in 

 England, the timber of the Scotch fir is reckoned of very liltle value. As an 

 ornamental tree the Scotch fir is gone much out of fashion, yet when allowed 

 to attain a sufficient age its rounded top and red-coloured bark and contorted 



