Papers.—1. “The Late Earthquake (1st September, 1888), and its Bearing on the Architecture of Wellington,” by W. M. Maskell, F.R.M.S.
The author, after alluding to the fact that the comparative immunity from destructive earthquakes enjoyed by the colony since 1855 had caused a general feeling of security, pointed out that no spot on the face of the earth is absolutely safe from earthquakes. When it was remembered that the most violent of all our New Zealand shakes happened in the neighbourhood of Wellington only about thirty-three years ago, and that a large portion of the Te Aro district in this city could probably not have been built over if that convulsion had not raised it several feet, one was inclined to wonder sometimes at the apathetic coolness of the inhabitants, and especially of the professional and municipal authorities. He was surprised to find that in the building by-laws of the City Council there was not, with one small exception relating to chimneys (which seemed to be a dead-letter), a word to indicate that any danger to life or property is to be feared from earthquakes. The Council seemed to have had a thorough dread of fires, but none of earthquakes. The City Surveyor had power to pull down chimneys built previously to the passing of the by law if they caused “reasonable danger of fire,” or from being built contrary to the provisions of the law; but no mention was made of earthquakes. All sorts of “architectural projections” were permitted on the outside of buildings, if approved by the City Surveyor, provided only they were placed high enough above the street. Professor Milne, of Japan, probably the highest living authority on the subject, had laid down the following principal rules to be kept in view in building stone or brick buildings in an earthquake country: (1.) So arrange the openings in a wall that for horizontal stresses the wall shall be of equal strength for all sections at right angles. (The meaning of this he took to be that it is better in buildings of several stories not to have the windows all arranged in regular vertical lines.) (2.) Avoid heavy-topped roofs and chimneys. (3.) Let archways curve into their abutments (“archways” here seeming to include window openings). (4.) Place lintels over flat arches of brick or stone. (Seemingly, Professor Milne's suggestion was that these lintels should be of iron or timber.) Professor Milne also suggested that “to build high houses would be to erect structures for the first earthquake to make sport of.” On the other hand, although there seemed to be nothing positively asserted as to foundations and solidity, it would appear that heavy solid buildings on deep foundations had less safety than light buildings on loose foundations. Criticizing some of the principal brick and stone buildings of Wellington in the light of the principles thus laid down, Mr. Maskell found that almost all these points appear to be neglected in at least the greater part of them. For example, in the Post-office, a building which looked as if designed to show how many windows could be arranged in the least space, the openings were placed in numerous vertical rows, their arches springing sharply from their abutments, and there was a heavy cornice running on the top of the somewhat thin walls. The large building of the National Mutual Insurance Company had also a heavy cornice, numbers of external ornamental projections, windows in vertical rows, and with arches not curved to the abutments. A building now in course of erection near the wharf had the brick partitions between the windows seemingly designed only to resist vertical pressure, and with little strength horizontally. The stupendous ugliness of the new Government Printing Office was such that perhaps even an earthquake might disdain to touch it: here again were vertical rows of windows with sharp-cornered arches, heavy pediment on each side. He understood, also, that this was a heavy, solid buildings, standing on very deep and strong foundations. Messrs. Harcourt's warehouse had the usual kind of windows, and would seem to the uninstructed eye to be dangerously lofty. In street buildings the openings, mostly very large on the ground floors for shop-windows, had above them several others, generally so arranged as to give a weak appearance to the fronts. And in many cases imitation
vases, globes, groups of figures, and other ornamental devices were placed along the edges of the roofs. It should be recollected that in cases where, as in the Post-office, a building is nearly all windows and openings, the iron rods and bands used to tie brickwork together cannot possibly run continuously in the external walls. On the whole, an inspection of the brick and stone buildings in the town of Wellington leads the lay mind rather to the impression that architects—at least, up to the present—have laid less stress upon safety from earthquakes than on their ideas of artistic effect. The matter of chimneys interested not only the dwellers in brick houses, but also those in wooden houses. Past experience of earthquakes clearly set forth that, as wooden houses swing at different intervals from those of their brick chimneys, if these last are in contact with the timbers of the house they are very liable to be simply knocked down. Yet probably there was not one house in a thousand in Wellington where the chimney was not built closely touching the woodwork of the roof. In conclusion, Mr. Maskell said that in the face of past history scientific pundits might demonstrate quite to their own satisfaction that a destructive shake is not at all likely to occur in New Zealand, just as some people can show to a moral certainty that the world will come to an end in some particular year. Still, it did seem not quite satisfactory that the by-laws of the Wellington Corporation should contain no kind of provision against earthquakes, and that a glance at the buildings in our streets should show that the points mentioned by high authority as desirable should not have been taken into consideration.
Mr. A. McKay, Assistant Geologist, in discussing the paper, said that Wellington was more concerned in the recent shocks in the Amuri district than most people supposed. He referred to the late earthquakes as in some way connected with the great lines of fault that run parallel with the Kaikoura Mountains, and thought that further movements along some of them may have been the cause of the late disturbance. He mentioned that the principal fault-line was prolonged across Cook Strait into the North Island, and in the South Island extended to the south-west far beyond the boundaries of the Amuri district. It was not certain that our city might not be visited next, for most surely we stood on the same fracture-line, and it was only a question of place whether we had the violence of a shock at one time, and there was a lighter one in the South, or vice versâ. The line of fracture passed from Tinakori Road to the mouth of Happy Valley, was next seen across the Strait at Lake Grassmere, on the Flaxbourne Estate, where it was traced for about sixty miles, to the Hanmer district. It passed within one and a half miles of the residence of Mr. Low, which suffered so seriously in the late convulsion, and at no great distance from Mr. Rutherford's station. The downthrow in the Kaikoura district was not less than 10,000ft., but between Karori and the city it was only 500ft. All this displacement had taken place in comparatively modern times, geologically speaking—perhaps within 500,000 years—and the movement was certainly not likely to cease for a considerable period—perhaps another 500,000 years.
Mr. T. W. Kirk said that the best thanks of the Society were due to Mr. Maskell for having drawn attention to this subject. If the city had really the slightest claim to the title sometimes given it by persons from other parts of the colony—viz., the “city of wind and earthquakes”—then the paper should possess special interest for the citizens, and he was surprised there was not a much larger attendance: the absence of architects was particularly noticeable. The author stated that there had not been, for more than thirty years, until the present month, any earthquakes in New Zealand of sufficient violence to do damage to property. He would like to ask Mr. Maskell if he did not think the earthquakes “which accompanied the Tarawera, eruption of sufficient violence. He thought it would have been as well if the candidates for seats at the City Council had been present, for after Mr. Maskell's paper
was made public they would most likely be asked to give their opinions on the architecture of Wellington. It seemed to him that a great deal more was made of the elevation of Te Aro flat than was necessary. Old residents had told him that the flat was originally a swamp, impassable except in a few places, and separated from the harbour by a bar; and that one winter there was an unusual accumulation of water in the swamp, with the result that it swept the bar away. From that time the flat ceased to be a swamp of any great extent, and subsequently drainage arrangements were carried out. The earthquake no doubt assisted in the alteration, but he thought it was the accident of the carrying-away of the bar that had most to do with rendering Te Aro flat available for building purposes.
Mr. H. P. Higginson thought that most of the defects in architecture pointed out by Mr. Maskell were the faults of the property-owners rather than of the architects. They insisted upon having structures of a certain class, and getting as much show as possible for their money. The immunity of Wellington from damage was probably due to the fact that the brickwork put up here was of a more substantial character than that in most other parts of the colony, particularly strong cement being used. Where the effects of earthquakes were felt most severely they were generally due in the main to bad workmanship.
Mr. Natusch (architect) said that, since reference had been made to the absence of architects, perhaps he might be permitted, although not a member of the Society, to say a few words upon the subject. Permission having been given, he said that when he arrived here some two years ago he naturally made it a point to ascertain what special provisions were made against earthquakes. He was astonished to find none; and, moreover, in course of conversation with Wellington men they said, “We have plenty of shocks—mere tremors; but there has not been a severe shock since 1855, when Te Aro was raised;” and it seemed to be generally taken for granted that serious earthquakes need not be anticipated. However, this hardly seemed reasonable to him; and, after considering the subject, he came to the conclusion that no more effectual “earthquake-proof” building could be devised than on the principle of framing. That is to say: Erect the frame of the building with wood, or with light T or angle-iron if preferred, very much in the same way as wooden houses are now erected; but on the outside of the framing secure thin slabs of concrete, with joints somewhat similar to those of rusticated boarding. Thus, in the event of a severe shock, the framing itself would sway more or less as the frames of wooden buildings do, and the slabs, having loose although weatertight joints, would also move with the frame. And he ventured to say that, except with a very severe shock (such a shock as would demolish the town), no damage would be done, and even if any of the slabs should be broken or cracked, they could be unscrewed and replaced with new at a trifling expense. Two or three people to whom he mentioned this were aghast at the idea of ugly buildings being put up with slabs of concrete. At first sight such an idea was quite pardonable even to the average architect or builder. But, in reality, architectural effects in any style, from the simple and pleasing Gothic to the most elaborate Roman or Grecian designs, might be produced. So much for the exterior. The interior could be finished with thinner slabs of the same material for walls, and the ceilings could be either plastered in the ordinary way, or formed with the patent steel webbing and plaster, which, in the event of a severe shock of earthquake, might when old hang down as old scrim does, but would not fall, as the ordinary plastered ceilings would do under similar circumstances. It would be seen, therefore, that buildings might easily be made to all intents and purposes “earthquake-proof.” The fears of the City Council as to the advisability of permitting the use of wood framings should give way before the fact that fire could not possibly touch the wood, because it would be encased
with the non-inflammable concrete on both sides. Well, it had been said, “But surely such a method of construction would be precluded by the expense.” But no; for one of the great beauties of this method was that it was more economical than building with brick or stone or solid concrete. His only objection to the method was the weight of the concrete. Happily this objection had been overcome in a highly satisfactory manner by Mr. Donaldson. A friend of Mr. Lascelles, the patentee of the system of building with concrete slabs in England—adopted, by the way, principally upon the score of economy, earthquakes not being usual in England—Mr. Donaldson, upon arriving here, set to work to improve upon Lascelles's system of manufacturing the concrete. By using pumice-sand with the best Portland cement, a concrete is produced which is of a much better natural colour, and, what is of greater importance, much lighter in weight than those made in the ordinary way. According to the proportion of cement used different degrees of hardness can be obtained, from that equal to Oamaru stone to granite. Thus, then, no obstacle so far as material, method of construction, and expense would stand in the way of this method for erecting both earthquake- and fire-proof buildings being adopted. What obstacle remained, then? Really none. But, as Mr. Higginson pointed out, architects are very much handicapped. In the first place, the City Council's by-laws merely provide against fire, by compelling the use of brick and stone, or solid concrete walls erected an the ordinary way, in the business quarters of the town; and he considered that the Council should be asked to permit the method of building in the manner pointed out. In the second place, those intending to build, were afraid to go out of the beaten track, and architects were afraid to push home to their clients any such vital changes.
Mr. Donaldson also asked permission to speak, and said the problem of building houses sufficiently fire-proof, wind-proof, damp-proof, and earthquake-proof requires very careful consideration. In the first place, heavy materials such as stone and brick are more easily overturned than wooden, structures, because if thrown slightly out of the perpendicular by an earthquake-shock their weight tends directly to bring them down, whereas a wooden structure with a properly-joined framework would bear a very considerable oscillation without any great effect being produced. But the objections to wooden buildings are,—
They are dangerous in case of fire.
They are not wind- or vermin-proof.
They rapidly deteriorate after being up a few years, and are too expensive to keep in repair.
The question therefore naturally arises: Can houses be erected with the tensile strength of a wooden framework, with a light yet strong material for the walls, proof against earthquake-shocks, as near as possible fire-proof, at the same time to exclude damp and wind, and offer great resistance to wear and tear? The method of construction used in iron-ship building answers all these requirements; but to build houses of thick plates of iron fastened on an iron framework would be very expensive, and the iron plates, being rapid conductors of heat and cold, would make such houses very uncomfortable. With a view to meet the requirements of the case, he had patented a concrete slab, made of a mixture of strong cement, pumice-sand, and sometimes gas-coke. This meets all the requirements. Samples of this material he exhibited. It has the following advantages:—
Unlike ordinary concrete, it is homogeneous, can be cut with a chisel or saw, can bear holes being drilled in it, and is perfectly uniform in strength.
It is firerfool; The slabs can be heated to a red heat without injury.
These slabs are made generally 1in. to 1½in. thick, and can be fastened to the studs in an ordinary wooden framework by
2½in. screws passing, through holes bored in the slabs. These holes are so made that the heads of the screws are sunk below the surface of the slab, and are then covered over with the patent concrete material used as a plaster. (If these slabs are used on the outside and the inside of the studs, leaving an air-space between, and also on the floors and ceilings, a perfect fireproof structure is obtained, the timber framework being completely protected from fire by the slabs.)
The natural colour of these slabs is somewhat lighter than Bath or Oamaru stone. They can be supplied, however, of any colour, and the most elaborate ornamentation can be moulded on them.
Besides being wind- and weather-proof to a more perfect extent than either wooden, stone, or briek buildings, and being also earthquake- and fire-proof, these houses have the advantage that, should damage from any cause be done to a wall, no effect is produced on the slabs above or in the neighbourhood. Each slab is supported quite independently of every other slab. Damage is, however, very unlikely, as the slabs are strong and tough.
Mr. C. T. Richardson pointed out that the old hospital, whice was now removed, was built somewhat after the plan advocated by Mr. Donaldson—namely, with what was called brick “nogging,” a kind of framework built in with brick. Upon the fact being brought before the City Council they had provided that any one could build in the city after the same style.
Mr. Natusch: That only applies to No. 2 Building District, not to No. 1.
Mr. Brandon said that the City Councillors were not all architeets or builders, and they had to frame their by-laws in a negative form. Of the two great dangers which they had to face, fire seemed more imminent than earthquakes, so they prohibited the erection of wooden buildings in the more populous parts of the city. They did not consider that it was necessary to detail the several points to be observed in the construction of buildings, so they left that part to the owners and architects. If the Council had endeavoured to frame by-laws to guide people in erecting structures warranted to resist earthquakes they would probably have laid themselves open to a great deal more criticism than they are now subjected to. As to the Post-office and Government Printing-office, the Government did not consider themselves bound in any way by the City by-laws, and would have gone on in their own sweet way in spite of the most earthquake-resisting regulations. Mr. Kirk had thrown some doubt on the raising of the ground at Te Aro on the occasion of the earthquake of 1855; but he believed he was right in saying that on the eastern coast of the province the beach was undoubtedly raised some 12ft., enabling settlers to ride round the coast where they had formerly been obliged to climb over hills, while Te Aro flat was elevated 4ft. or 5ft. In conclusion, he could only regret that, according to Mr. McKay's account, we had still 9,500ft. to slip down.
The President was sorry that there were not more persons present who were acquainted with the technical part of the subject. Of course, his only knowledge of the subject was that of an ordinary layman. As to the elevation of Te Aro, it would be excessively uncomfortable for the residents if they had to go down again, even 4ft., and there was nothing that he knew of to show that the land would not go down in the next earthquake in the same way as it rose thirty-three years ago. He was very glad that last week's shake occurred at Amuri: if it had happened in Wellington it would have knocked down about half the buildings in the city. Professor Hutton had consoled the people of Christchurch with the assurance that the centre of the late shakes was so distant as to
render their city quite safe; but Mr. McKay had shown that Wellington was by no means so far from the fissure, but was, on the contrary, very much on the line of it. His only object had been to call attention to the fact that the buildings in Wellington were not put up with a view to resisting earthquakes. Some people might say that it was not necessary to keep this end in view, and if they thought so they were entitled to their opinions. He was glad to find that no serious objection had been taken to the views he had offered. Every one present seemed to agree that our buildings were not erected in such a manner as to provide against severe shakes; therefore, if those shakes came, the people of Wellington would only have themselves to thank.
2. “On the Extent and Duration of Workable Coal in New Zealand,” by James Park, F.G.S. (Transactions, p. 325.)
Mr. Higginson asked on what data Mr. Park's estimate of the amount of coal in each field was founded, and whether he had taken into account the depth to which the coal might be worked, and the probability of there being two or more seams of coal in the same field. He pointed out that a consideration of these facts would greatly affect the estimated amount.
Mr. Park, in reply, said that his estimate was based upon the surveys made by the different geological workers who had examined and reported on the various coalfields, which only included such areas as were known to contain coal.
Mr. McKay did not think that Mr. Higginson's most important question had been answered—namely, as to the number of seams that might be present in particular coalfields.
Mr. Park further said that he had stated in his paper that there was usually but one seam near the base of the series; and that otherwise his estimate of the amount of coal had been based on what might be worked level-free.