Dec. 12, 1884.] 



♦ KNOWLEDGE ♦ 



487 



whence air will rush out of the cylinder, and the piston 

 will be driven up again by virtue of the greater jiressure 

 existing beneath it. Reverting to Fig. 3, it will be seen 

 that a pressure of the ball, F, will cause the pin over the 

 brass stud, E, to be forced downwardi?, the elastic spring 

 connecting H with J K causes the brass rod to revolve, 

 carrying with it the shutter, A. The beam of light will 

 then pass through the opening, previously covered up by A, 

 and impress a picture on the plate waiting to receive it. 

 The revolution of A, however, allows another shutter, B, to 

 fall into its i)!ace, and so to close the orifice once more. A 

 flat spring on the side of the frame carries a small peg, 

 which, as B descends, is pressed into a hole in the side of 

 the shutter, so as to prevent it rebounding. L M N O are 

 small brass buttons, around which, when the duration of 

 exposure is required to be very brief, an elastic band is 

 passed, with the result that the rapidity with which B falls 

 is considerably accelerated. D is an indiarubber buffer 

 against which the shutter A strikes, thereby preventing it 

 coming into contact with the other shutter, B. P is a small 

 stud by means of which B may be raised to its ordinary 

 position. This piece of apparatus is wonderfully well-made, 

 and answers its purpose admirably, and if there is anything 

 which the company supplies that I should feel justified in 

 recommending, it is this n^ally instantaneous shutter. Its 

 rapidity in responding to the demands made upon it is 

 astonishing. 



I have, perhaps, exceeded the limits usually prescribed 

 in this journal, but the increasing and deserving popu- 

 larity of the art, and the often-expressed desiie to hear of a 

 few of its many applications, aflford, I trust, ample apology. 

 One last word I would utter, aud that is a warning to 

 such of my readers as may feel disposed to provide them- 

 selves with a photographer's impedimenta, to deal only 

 with good houses if they really wish to ensure success. It 

 were, perhaps, somewhat invidiou.s to specialise any one 

 establishment, but since the Stereoscopic Company offer so 

 many exceptional facilities to the amateur, I may, perhaps, 

 be permitted once more to mention them. 



CHAPTERS ON MODERN DOMESTIC 

 ECONOMY. 



VI.— THE FEAMEWOEK OF THE DWELLING-HOUSE 

 (^continued) . 



GENERAL PEIXCIPLES OF CONSTKUCTION. 



THE almost universally adopted form of window frame, 

 with its upper and lower sashes balanced by means of 

 heavy lateral counterpoises, has many disadvantages ; so 

 many drawbacks are there, indeed, that it is a matter for 

 surprise why they have not long since been superseded by 

 some more rational contrivance. Like many other old- 

 established and defective systems, a sweeping reform can 

 scarcely be applied successfully here ; the type of the frame 

 has been taught to, and mastered by, the practical workman 

 until it has become part and parcel of his operative creed. 

 From a commercial point of view, also, the rapid progress 

 of valuable reform is undesirable, and accordingly receives 

 a jiowerful check. If the accepted type were abolished 

 suddenly, the demand for special pulleys, weights, sash bolts 

 and fasteners, and the sashes and frames themselves would 

 cease, and so much dead stock would crowd the market. 

 Again, the manufacturers of such wares would sutler di- 

 rectly, in being obliged to discard their present working 

 plant and adopt new models. Even partial innovations 

 make but tardy progress, or we would find sashes with 



universal movement, such as those alluded to in our last 

 communication, more in vogue. 



Windows ought to be constructed upon the following 

 principles: — (i), to assist ventilation ; (ii), to exclude draft, 

 dust, and rain ; (iii), to admit of being thoroughly cleansed 

 with safety ; (iv), to be capable of being opened to the 

 full extent of the framework aperture without any incon- 

 venience ; and (v), to atiurd scope to the artistic designer. 

 All of these items ought further to come with the bounds of 

 reasonable expenditure ; that is to say, an outlay which 

 shall not exceed the limitation placed by architects upon 

 such structures. A window-frame which incorporates all 

 the advantages enumerated above, has not yet, to our 

 knowledge, been introduced to public notice. AVe shall 

 reserve our ideas, in special illustration of this subject, to a 

 future chapter. 



A great many dwelling-houses are provided with a flight 

 of stone steps to their main entrances and doorways ; but 

 the majority of smaller abodes and shops have merely a 

 doorstone, slightly elevated above the street pavement. In 

 all cases, but especially where there is a constant traffic, as 

 at shop doors and greatly frequented public staircases, the 

 edges of the steps invariably give way after a few years of 

 incessant use, and may, in the course of time, become worn 

 to such a degree as to be positively dangerous. Something 

 harder and more durable than the ordinary building stones 

 now employed is, therefore, requisite, and we consider it to 

 be the duty of every modern builder to take advantage of 

 any invention that may secure immunity from prejudicial 

 wear and tear. Messis. Doulton & Co., of Lambeth, S. E., 

 have introduced a valuable invention in their patent im- 

 perishable " Silicon Tread," which may be used with stone 

 or terracotta steps, either in or out of doors, and may be 

 readily adapted to any existing stone staircase or doorway 

 slab. We would draw the attention of tradesmen, and 

 owners of commercial buildings more particularly, to this 

 invention ; for, through its employment, they will secure a 

 doorstep made of a specially prepared clay, which produces 

 a tread so hard as to be practically everlasting. When 

 fixed in position it is immovable, and afl'ords a firm foot- 

 hold, on account of its longitudinally corrugated upper 

 surface. 



We may now pass on to the consideration of the relative 

 disposition of the rooms and passages of the dwelling- 

 house, without, however, entering into any details of archi- 

 tectural design ; for we are here discussing principles 

 rather than examples. All the doorways into halls and 

 passages ought to be provided with adjustable fanlights ; 

 for these do not only serve to admit difi'used daylight, but 

 are accessories to a well-regulated system of ventilation. 

 The value of fanlights above doors leading into habitable 

 rooms has been much disputed ; a little reflection, however, 

 will soon convince one that they only act as ventilatoi-s 

 when the windows are open or the fires burning. At all 

 times they give access either by regular currents, or 

 through diffusion, to air from the hall and passages, which 

 is always open to possible contamination. On the whole 

 they are to be discountenanced, as violating one of the 

 most important principles of sanitary house construction, 

 viz., that which seeks to establish the utmost isolation of 

 the separate chambers in the building. Each room ought 

 to have its own special inlet for fresh air, and an outlet for 

 vitiated air ; and although this is not absolutely possible in 

 every dwelling-house, that is no reason why a contrary 

 state of affairs should be permitted to obtain. 



Where a choice of position can be exercised the principal 

 windows of the house ought to face to the north. A north 

 light in this country is not only more agreeable, but it con- 

 tributes towards the preservation of such household fur- 



