Sept. lo, 1874] 



NATURE 



393 



selection, has been taking place during the last twenty or thirty 

 years, or more. In contrast with this 1 ha\'e now to mention a 

 reform towards abatement of dangers at sea, which at present is 

 only in an incipient stage of its practical application, but which 

 I am suie must soon grow into one of the important reforms of 

 the future. 1 reler to the provision of means whereby every 

 important lighthouse shall, as soon as it is descried, not only 

 make known to the navigator that a light is visible, but also that 

 u shall give him the mucii more important information of what 

 light it is ; that, in fact, it shall distinguish itself to him from all 

 other lights either stationed on land or carried by ships out 

 at sea. Tht lendetirg of lighthouses each readily distinguish- 

 able Irom every oiher light, by lapid timed occultations, was 

 urged on public attention by Charles Babbage about twenty 

 or twenty -three years ago, in connection with a like 

 proposal of his for telegraphic signalling by occulting 

 lights. His admirable idea, however, so far as it related to 

 the distinguishing of lighthouses, has unhappily been left almost 

 entirely negleeteel until quite recently. Although 1 say it was 

 almost emiiely neglectea, yet very important steps in the direc- 

 tion of the object pioposed were taken many years ago by 

 Messrs. Stevenson, engineers to the Commissioners of Northern 

 Lights, and the flashing and intermittent lights introduced by 

 them, and now used, although too sparingly, in vaiious parts oi 

 the world, constituted a very great improvement in respect to 

 distinctiveness. The first piactical introduction of an intermittent 

 extinction of a gaslight, which is a method now likely to become 

 fruitlul in important applications with further developments, was 

 made ni;iny years ago tjy Mr. Wilson at I'rcon; and an admirable 

 application ot this plan by the Messrs. Stevenson to carry out 

 the principle of lapid signalling is to be seen in the Ardrossan 

 Harbour light, which is alternately visible for two seconds, and 

 then for two seconds is so ntaily extinguished as to be invisible. 

 The whole period— four seconds — is, 1 suppose, the shortest of 

 any lighthouse m the world. This light lultils the condition of 

 being known to be the light which it is, within five or ten 

 seconds ot its beirg first perceived ; and thus, in respect to 

 distinctiveness, 1 tiust that I may without mistake say it 

 is the best light iir the world. Mr. John Wigham has 

 succeeded in constiucting large burners for the combustion of 

 gas in lighthouses in general, ircluding those of the first order, 

 and embracing both fixed lights and revolving lights. He has 

 also, in both these cases, applied with the most striking success 

 the principle ot occultation. Dr. Tyndall, in his reports to 

 the Board of Trade, has dwelt fiequently and emphatically on 

 the ease with which gas lends itself to the individualisation of 

 lights. By its application, he affirms that by simple arrange- 

 ments it would be possible to make every lighthouse declare its 

 own name. Within about the last two or three years the 

 subject has been taken up energetically by Sir William Thom- 

 son. He has become sttongly impressed with the enormous 

 importance of the object in question. He has perseveringly 

 laboured in making trials in various ways, both by the methud 

 of partially extinguishing gas flames and by the method of 

 revolving screens ; and 1 have pleasure in stating that, as a 

 result 01 his eftbrts, a self-signallirig apparatus is now con- 

 structed for the Bellast Harbour Commissioners, who are pre- 

 paring to bring it into immediate use at the screw-pile light- 

 house at the entrance of the harbour of Belfast. 1 shall not 

 now enter on any description of this arrangement, as 1 under- 

 stand that the apparatus, which has alieady been temporarily 

 elected lor trial in the lighthouse, and has shown good re- 

 sults, is to be exhibited and explained to this Section by Mr. 

 Boitomley, who, as a member ot the Board of Haibour Com- 

 missioners, has taken an active part in the promotion of the 

 undertaking. 



I w ish next to make mention of the very remarkable works 

 at present in progress in the harbour tf Dublin, under the 

 designs and under the charge of Mr. Bindon Stoney. In order 

 to lorm quay wals with their foundations necessarily deep under 

 water, he constructs on land gigantic bloeks of artificial stone, 

 or, as we may say, of concrete masonry, each of which is about 

 350 tons in weight, and which are accurately formed to a 

 required shape. Alter the solidification ot the concrete, he 

 cairics them away and deposits them on an accurately levelled 

 bottom of sea, so that they fit closely together, and form so 

 much of the quay wall in height as to reaeh above the low tide 

 level ; and so as to allow of the completion of the wall above 

 by building in the usual manner by tidal work, and to allow of 

 the whole structure being carried out without the use of cotTer- 

 (Janis. 'Ijieie ojerat;oi.s are on a scale ol magnitude far sur- 



passing anything done before in the construction and moving 

 of artificial stone blocks. They are carried out with machinery 

 and other appliances for the removal and the placing of the 

 blocks, and for other requirements of the undertaking, which 

 are remarkable for boldness of conception and ingenuity of con- 

 trivance. The new methods of construction devised and applied 

 in these works by Mr. Stoney are recognised as being admirably 

 suited for the local circumstances of the site ol the works in the 

 harbour of Dublin, and their various arrangements form a very 

 important extension of the methods of construction available to 

 engineeis for river and harbour works. 



While progress has been made with gigantic strides in many 

 directions, in engineering and in mechanics generally ; while 

 railways, steamboats, and electric telegraphs have extended 

 their wonders to the most distant parts ol the world ; and while 

 trade, with these aids, is bringing to our shores the produce even 

 of the most distant places, to add to our comlorts and our 

 luxuries ; yet, when we come to look to our homes, to the places 

 where most of our population have to spend nearly the whole 

 of their lives, I think we must find, with regret, that, m matters 

 pertaining to the salubrity and general amenities 01 our towns 

 and houses, as places for residence, due progress in improvement 

 has not been made. Our house drainage arrangements are habi- 

 tually disgracefully bad ; and this 1 proclaim eujphaiically, alike 

 in relerence to the houses of the lich and the poor. We have 

 got, since the early part of the present century, the benefit of the 

 light of gas in our apartmeuts ; but we allow the pernicious pro- 

 ducts of combustion to gather in large quantities in tlie air we 

 have to breathe ; and in winter evenings we live with our heads 

 in heated and vitiated air, while our Icet are ventilated with a 

 current ol fresh, cold air, gliding along the floor towards the fire- 

 place to be drawn uselessly up the chimney. A very few people 

 have commenced to provide chimneys or flues .to carry away the 

 fumes of their more important gaslights, in like manner as we 

 have chimneys for our ordin.iry tires. In mentioning this, how- 

 eier, as a suggestion of the course in which luiprovement ought 

 to advance, 1 leel bound to offer a lew worda 01 cautiun against 

 the introduction of flue pipes lor the gas flames lashly, in such 

 ways as to bring danger of their setting fiie to the house. People 

 have a strong tendency to require that such things as these should 

 be concealed from view. In this case, however, special care 

 should be taken against rashly placing them among the woodwe'ik 

 between the ceiling of the apartment and the floor of the room 

 above or otherwise placing them in unsafe proximity to com- 

 bustible materials. In many cases it would be better to place 

 the Hue exposed to view underneath the ceiling, and by intro- 

 ducing some accompanying ornamentation, to let the flue Le 

 regarded as a beneficent object not unpleasing to the eye. 



The atmosphere of our large towns, where people live by 

 hundreds of thousands all the year round, is not yet guarded 

 against needless pollution by smoke, jealously, as it ought to be. 

 ^lany of the wealthier inhabitants take reluge in living in the 

 country, or in the suburbs of the town, as far away as they 

 can from the most densely built and most smoky districts ; but 

 the great masses of the people, including many of all ranks, 

 must live near their work, and for them at least greater ex-..r- 

 tions are due than have yet been made towards inaintaming 

 and improving the salubiity and the amenities of our towns. 

 As to the abatement or prevention of smoke fiom the lurnaces 

 of steam-engines, the main requisites have long been very well 

 known; but sufficient energy and determination have not }et 

 been manifested towards securing their due application in piac- 

 tice. In too many cases futile plans have been tried, and on 

 being soon abandoned have lelt a strong impression against 

 the trying of more expeiiments; and this may account in part 

 for the introduction ot real improvements havmg been so slow. 

 Smoke occurs when fresh coal is thrown suddenly, in too large 

 quantity at once, upon a hot hre. By extreme care a fireman may 

 throw coal into his furnace so gradually as to make very litiie 

 smoke ; but mechanical arrangements lor introducing constantly 

 and uniformly the new supply of fresh coal have been devised, 

 and several of these have been such as to reduce the sn.oke 

 emitted to .almost nothing. I have seen in the neighbourhooa 

 ol Glasgow, at a large manufacturing establishment at Thornlie- 

 bank, one method which is applied to about thirty o:dinary 40- 

 horse-power boilers, in which upwards of 100 tons of coal are 

 daily burned, and Irom the chimneys of which not more smeke 

 is emitted than fiom many a kitchen fire. This method is under 

 the patent of Messrs. Vicars, ol Liverpool, and it seems to work 

 very well. It has been about two years in work there. It wiS 

 inliodutcd ;it a time when eool was exceedingly lii^h 111 pric ; a; 



