WINDOW. 



o. INI' 





laut in the religious anil other monumental rtruotunw of the Egypt 

 ian*, Greek*, and Romans, which were not of a nature, to requii 



v arr exceedingly important features in the Gothic ami tlnr 

 styles, ami that not nly I.T one, but every data of ImiMinu--. In tin- 

 Pointed Gothic more especially they are o characteristic 1 

 general forms and proportions, as well in their decoration nnd <! MiU. 

 as to be in that style equivalent to what the orders ore in the 

 architecture of mui |<iity : tlie division of i;.,thi' into periods, as 

 First, Second, nml Thirvl Pointed, or Marly Kni;!i-li. Decorated and 

 Perpendicular, depends indeed mainly on the window-forms. [< 

 Ai-.nii llojiANKsQi-K ABCHITKCTURK.] Gothic without 



windows would be as deficient in expression as Grecian architecture 

 without column*. Grecian architecture, on the contrary, liardly 

 admits windows, since, instead of adding to, they rather mar iu 

 expression, an- 1 detract from its character. There are, indeed, some 

 examples of windows, for instance in the Ercchtheuin at Athens, yet 

 no more than barely to serve as authorities, and to show how 

 apertures of the kind were designed. Besides being of exceedingly 

 rare occurrence in Grecian architecture, the windows themselves were 

 very few in number, and never placed so as to form more than one 

 tier or story of them ; consequently the effect was totally different from 

 that attending two or more continuous ranges of windows ploc.,1 .,;:, 

 over the other. This arrangement was, however, adopted by the 

 Romans in such buildings as their amphitheatres, and also iu their 

 basilicas, and in the former with a very fine effect, as may be 

 Men in the Colosseum at Rome, and the amphitheatres of Verona and 

 Nlmes. 



It ia one very great advantage of the Pointed Gothic style, that 

 there the windows derive strong architectural expression from the 

 apertures themselves ; which, with the [millions, transoms, and tracery 

 inserted in them, mainly form the design and decoration ; while the 

 external mouldings and ornaments contribute to them only in a subor- 

 dinate degree. Consequently, if otherwise quite plain, the windows 

 can never appear mere vacant spaces. Widely different is it in those 

 styles where the ornamental design is confined to the mere exterior or 

 framing of the aperture ; in which, however they may be so decorated, 

 the openings will, if of very large dimensions, always have a vacant 

 look, and the glazing of the windows will appear to be in want of ade- 

 quate support. It is another advantage peculiar to Pointed Gothic, 

 that it allows windows to be of any dimensions of the smallest as 

 well as the largest, and windows of very different sizes and propor- 

 tions to be introduced into the same elevation. [GOTHIC ARCHITEC- 

 TURE; ORIEL.] 



In the Italian style, windows, by which we mean the window opening 

 and the draangi around them, which last term is employed to 

 designate the whole of the decoration bestowed on such apertures, or, 

 in other words, the entire " composition," form as essential a feature as 

 in Gothic, though admitting of comparatively little of the diversity of 

 size, form, and character. French, German, and English Renais- 

 sance exhibit much greater variety of illustration than the Italian. 

 [RENAISSANCE A RCHITECTCBE ; ELIZABETHAN ARCIIITKCTI'RE ] In 

 Italian buildings of the better class, the principal story, or that imme- 

 diately over the basement or ground-floor, is marked by windows more 

 highly decorated and of loftier proportions than the rest. For these 

 the apertures are generally made from 2 to 24 squares, or even some- 

 thing more, that if, their height is something more than double their 

 breadth ; those on the next floor rather less than two squares ; and for 

 the third they are made mezzanines either a perfect square or very 

 little more. The character and proportions of ground-floor windows 

 depend very much upon the manner in which that part of th< 

 lion is treated ; if it be no more than a low rusticated basement, the 

 windows will only be of mezzanine form, without dressing ; or at the 

 most a few mouldings surrounding the apertures, the rusticated surface 

 of tlie wall itself here producing a sufficient degree of finish and deco- 

 ration ; or if more be required, it is obtained by distinguishing the 

 rustics around the windows, making them smooth if the others be 

 rough, and vice rend. Thus, while the windows are essential, they arc 

 Hill kept subordinate features in the design. What has been 

 regard to the sequence of the different tiers of windows in an elevation, 

 is to be understood only generally, there being many exceptions, nnd 

 not a few anomaloua cases. In the facade of the Palazzo Massimi at 

 one of Peruxzi's best works, there are two tiers of mezzanine 

 windows above those of the principal floor ; in the celebrated Palazzo 

 Farnene, on the contrary, the second floor window* (which ore also the 

 uppermost) are somewhat loftier than the others, at least in their aper- 

 owing to these last being arched, and are further remarkable as 

 having pedimenU, which are seldom used for windows higher up than 

 the first floor. In Sangallo's facade of the Palazzo Kacchctti, there is a 

 range of mezzanines between tlie windows of the first and the upju T- 

 most floor, and instead of being made principal in the design, (In- 

 former are considerably lex than those of the ground- floor, an. I an- 

 narrower M top than at bottom. The facade nf the Palazzo Negroni, l.y 

 Ammanati, is similar in its general character to the preceding, there 

 being a row of mezzanine and square windows between the first and t hird 

 floor ; and it aUo resembles it in the importance given to the ground- 

 floor windows. In regard to window* of the but-mentioned class, the 

 Palazzo Buoncompagno at Rome, a work attributed to Bramante, offers an 

 unusual example, for there the lower floor and its windows are made the 



11. \t principal feature* after those immediately above them : in both 

 the aperture* themselves are round-headed, with imposts and ,,i. lm,.!t .. 

 I. ut it inked l>y pilaster* supporting an entablature. .. 

 form of the ekambrault, or dressing, becomes square-headed ; i: . 



.-e between theae two tiers of windows is, that those above have 

 pediments i alternately angular and segment*!), while the others have 

 none. Triple, or Venetian windows, as they are called, and grouped 

 ft, are sometimes introduced iu Renaissance bui!-l:n - with 

 excellent effect ; and whore a great degree of magnificence is desired, 

 cnryatide* are substituted for columns as decoration*, l-'rom tlie time 

 of I'.dladio, balustrades have been added to windows, addin.- 

 greatly to their picturesquencas of character, but sometimes with a 

 .very different result [iT.vi.i , . MCE ] 



WINDS. THADK [\Vi:.. 



WIXDSAILS are the rally four in nuiiil.cr. which. In-in^ 



tiiriu-d liy the action of tin- wind, g 



mill. The wind being supposed to l>l\v in a direction ;. .-. Jl.-i to tin- 

 axis about which the sails are to revohv, it is evident that the plane 

 of each sail must have a certain inclination to that axis, or to the plan.- 

 of the revolution, in order that a resolved part of the wind's force may 

 act in the latter plane piTju-ndiriil irly to the radii or arms which carry 

 the sails so as to turn them constantly in one direction about t). 

 If the pressure of the wind on the sails, supposed to be at rest 

 to be alone considered, the determination of the angle which the plane 

 of each sail should make with a plane perpendicular to the axis, or to 

 the direction of the wind, in order that the pressure might be a 

 maximum, would bo comparatively easy. For by tlie resolut: 

 forces it is easily seen that the pressure perpendicular to the radii, 

 and in the plane of their revolution, varies with the term sin : 9 cos 9, 

 where 9 is the angle which the sail, supposed to be a plane surface, 

 makes with the wind or with the axis of revolution : nnd th 

 of this quantity being mode equal to zero, the value of 9 is found 

 to be 54 44' nearly. 



But it is evident that the effect of the wind in giving a re-. 

 motion to the radii must depend on its pressure, and also on tin- 

 velocity of the surface against which it acts ; and the angle which tin- 

 plane of the sail should make with the direction of the wind, when its 

 pressure on the sail iu motion is a maximum, must be determined by 

 an investigation similar to that which follows. 



Let A B, A'B', parallel to one another, represent the direction of the 

 wind ; wnx, W'H'.X', also parallel to one another, be two positioi, 

 section of the sail, which by the pressure of the wind is made to move 

 so that B, B', are in a line perpendicular to A B. Now if it be supposed 

 that A'II' is the space described by a particle of air while B would move 

 to b (or 4' to B') in the same direction, or from n to B' in a direction 

 perpendicular to AB ; the lines A'B' and b'n' will, respectively, represent 

 the velocities of the wind and sail in directions parallel to A'B', while 

 1111' will be the velocity of the sail in the direction of this l;i.t line. 

 Draw A'C* perpendicularly to w\ or wV, produced, and nir.tiiii; the 

 former line in c ; then A'C' and cc' will be respectively the velocities 

 of the wind and sail perpendicularly to the line w.x or wV. and con- 

 sequently A'C will be what is called the velocity of the wind in the 

 Rail. Therefore, the pressure of a fluid being proportional to tin- 

 square of the velocity, the pressure of the wind in the direction A'C' 

 will vary with A'C'; and this being resolved in the direction A'I> or mi', 

 will l>c expressed by A'C' cos c\r>, or \ But A'H being 



constant, A'C varies with sin A'BC; therefore the effective pressure of 

 the wind will vary with sin' A'BC sin u'eb. 



Let the angle A'BB' be represented by a, B'B//' by 9; then \'in- 

 a 9, and the expression for tlie pressure becomes 



sin ; (a 9) sin 9. 



Jinking the differential of this expression equal to zero, and reducing, 

 we have 



tan (a-9) = 2 tau 9, 



when the pressure is a maximum. 



Draw a'xr perpendicular to BC, so that B'x and xv may respectively 

 represent tan (o- fl)and ton 9; and let A'H', BB' be res|'etively 

 Rented by t> and by r' ; then 

 >, B'x=t/ sin 9, 



= 3t>'siu9. 



