mTHE SKIASCOPE

THE SKIASCOPE IN USE

A LONG and unfamiliar name for a small and not un-familiar thing. The word means " shadow-seer," the seerfrom and into shadows (cneta, shadow; a/coirec*, to see) . Theskiascope uses looking from shadow as a means of lookinginto shadow. It has been devised for the purpose of dem-onstrating a visual principle not yet given the importanceit deserves by museum people.

For good seeing, it is more important that the eyes should be suf-ficiently shaded than that the object should be abundantly lighted.

To prove this principle we must provide some meansof diminishing our field of view so that the eyes are shaded

approximately from everything except the object lookedat. The skiascope does this in handy fashion, with theresult that we see things well through it in almost anylighting. The instrument has, therefore, at once a prac-tical and a theoretical value. The user not only sees bet-ter with it but also learns that the chief obstacle to seeingthings well is generally glare from elsewhere.

THE SKIASCOPE 239In artificial lighting the importance of keeping sources

of light out of the eyes is now admitted. The lesson wastaught conspicuously at the Panama-Pacific Exposition,and later at the Statue of Liberty in New York Harbor.We have found that the best way to show things at nightis not to light them up in the old fashion, by distributingsources of light over them to dispute the observer's visualstrength with the objects to be seen, but to show themin a glow, which, though it may be dimmer, contains nobrilliant points to deaden the susceptibility of the eyes.In natural lighting it may be impossible to conceal the

sources of light : for example, the low windows or the ceil-ing lights of a side- or top-lighted museum gallery. Analternative in case of need is to shade the visitor's eyes;and this the skiascope does.The instrument consists essentially of a small, light box

with flexible sides, open at the ends, lined with black anddivided longitudinally by a central black partition; oneend of the box being shaped to fit closely against the eyes,and the other broadened to give a sufficient field of view.The flexible sides permit of shutting the skiascope upwhen not in use. Wires forming a handle turn up out ofthe way, reducing the instrument to about the size of asmall thin book, capable of being carried in a good-sizedpocket.Eye-shades of various forms are common. The skia-

scope is a novelty only in the handy way in which it re-stricts the observer's view to a small part of the normalfield of vision. At a distance of six or eight feet from awall he sees only a patch of it perhaps four feet high andthree feet broad. If the space between two adjacent win-dows of a side-lighted room is not too narrow, he caninspect an object hung between them without getting theglare from either. The view of an object so placed which

240 MUSEUM IDEALSthe skiascope gives is a revelation. Generally, the windowwall of a gallery is regarded as so much space lost for seri-ous exhibition purposes; or at best as appropriate onlyfor things not needing, perhaps not deserving, to be seenin detail. The skiascope makes the space on a window wallas valuable within limits as any. A window wall is lighted(unless there is cross-lighting) only indirectly and by re-flection from the rest of the room; but this illuminationproves in most cases quite enough. Not lack of light butlack of sight accounts for its unavailability to the un-shielded eye.But the value of an eye-shade like the skiascope is not

confined to window walls. Raising it to the eyes in a top-lighted gallery, a noticeably deeper tone spreads over the

pictures, and accentuated lights and shadows appear onthe" sculptures. We realize that generally the fraction ofceiling light within our view and perhaps also illuminatedparts of walls and floors, have robbed the canvases andmarbles of a share of their designed effectiveness.The museum use of an eye-shade, however handy, will

doubtless always be a restricted one. For the occasionaladvantages it gives, people will hardly care to burdenthemselves with an apparatus conspicuous in use and need-ing to be carried about. Yet in galleries abroad the old-fashioned tubular eye-shades are sometimes handed visi-tors for use in inspecting individual masterpieces. Incertain galleries skiascopes might, it would seem, be addedto the facilities, such as chairs and catalogues, offered forthe visitor's comfort and information. When not in use,the skiascope might hang at the doorways. Specially in-terested persons would certainly appreciate an aid togood seeing; and the offer of it would give the museum awider freedom in the use for exhibition purposes of anyparts of the interior particularly subject to glare.

THE SKIASCOPE 241The theoretic value of the skiascope is incontestable.

The demonstration it gives that avoidance of glare in thevisitor's eyes is a prime necessity in museum planningand installation will surely in future lead to the adoptionof means to minimize the evil. The skiascope is hereoffered as a factor in an anti-glare propaganda.

THE SKIASCOPE CLOSED

As the skiascope will very likely never become a commercialproposition, it may be of use to describe its make and makingin detail.

Parts

1 . Two pieces of three-sixteenths inch board six and one halfinches long by five inches wide, one end shaped as shown (fullsize for convenience of tracing) in Figures 1 and 1 bis. Each isstained oak on one side and the edges. These are respectivelythe forehead and cheek pieces of the instrument. The foreheadpiece has two grooves, one sixteenth inch deep, on the raw side,and the cheek piece one, as shown.

2. A piece of black flannel, not too heavy, shaped as shown inFigure 2. This makes the flexible sides, the middle partition andthe lining of forehead and cheek pieces.

3. Two wire attachments (size 14) forming together thehandle of the skiascope, shaped as shown in Figure 3. The threeends of these wires are secured in the grooves of the boards byminute staples driven through and clinched.

Q2*

\/

THE SKIASCOPE 245

Construction

4. The pair of lining blocks each shaped as in Figure 4 andwith three-sixteenths inch central holes from end to end are usedas forms over which to stretch into position the flannel lining of

the instrument while it is being cut and glued together as here-after described; and also later in glueing the forehead andcheek pieces to the lining.

5. The bed-block shaped as shown in Figure 5 is used in glue-ing the forehead and cheek pieces to the lining when this is

o 3"

formed up over the lining blocks. It brings the upper surface ofthe lining blocks to a level position in order to hold a weight orclamps conveniently.

246 MUSEUM IDEALS6. The two wire clamps, each shaped as shown in Figure 6,

are used in the process of covering the lining blocks with theflannel used as lining in order to hold them closely together as

hereafter described. The two prongs of one are inserted intothe central holes of the larger ends of the two blocks and thoseof the other into the holes at the smaller ends.

To form up the liningCut a piece of the flannel somewhat larger than the pattern

shown in Figure 2: as there indicated by dotted lines. Flannelbeing a stretchy material, the attempt to fit it if previously cutaccording to the pattern is likely to give trouble. Flannel ischosen rather than any stiff material for the less disturbing lineswith which it frames the field of view. Cut a piece off the flannelalong the line AB. With a red crayon draw a line on the flan-nel parallel to and half an inch back of the line AB. Fasten the

flannel along this line to one edge of one of3 '' the rectangular sides of one of the lining

blocks with a few thumb tacks. The smallend of the block should lie toward A, thelarge end toward B. Wrap the block tightlyin the flannel. When wholly covered withone thickness, place the other lining blockagainst the covered block, small end tosmall end, and its rectangular sides in a

plane with the rectangular sides of the covered block. Insertthe two clamps in the two ends of the blocks, thus fasteningthem firmly together. Now, with the rest of the flannel, cover

THE SKIASCOPE 247the second block tightly, securing it at the last edge reachedby another set of thumb tacks. The flannel being larger thanthe pattern will lap over the ends of the blocks and more thancover the last face of the second block. Trim off the superfluousflannel at the four edges of both ends and also at the last edgesecured by the thumb tacks, leaving here also a border halfan inch wide as on the front edge AB. Now, glue the two flannelborders down, letting the glue run closely along the intersticebetween the blocks. This secures the line CD of the finishedlining shown in Figure 2 to the line C'D' in that figure, and theline EF to the line E'F'. When the glue has set under pressure,remove the thumb tacks. With pieces of pasteboard cut to thetwo lining curves shown by dotted lines in Figures 1 and 1 bis,mark out these curves in red crayon at the smaller end of thecovered blocks, now secured together, one curve on each rec-tangular face. Run the crayon also along all four longitudinaledges of the covered double block. This is necessary becausethe lining must be taken off the double block to be further cutand needs to be replaced in exactly the same position for thefinal glueing on of the forehead and cheek pieces. Now takethe clamps out of the blocks and slip the lining from them.Then, at the larger end of the lining, cut the central partitionaway from the top (forehead face) and bottom (cheek face) ofthe lining to a point one and a half inches from the end. Then,cut straight across the central partition from the end of one ofthe previous cuts to the end of the other. Repeat the process atthe small end of the lining, with this difference: the cut alongthe top (forehead face) of the lining should extend to a pointone and three eighths inches from the end, and the cut alongthe bottom (cheek face) to a point two and one eighth inchesfrom the end. After the central partition has thus been cutaway at both ends, cut out the lunettes marked out in red crayonon each face of the lining. Carefully replacing the lining blocksin the lining and clamping them and seeing that the ends andthe marked edges are exactly in place, put the whole on thebed-block as shown in Figure 5 in readiness for the final glue-ing on of the forehead and cheek pieces.

To glue on the forehead and cheek piecesAs the wires in the grooves project slightly above the surface

of the forehead and cheek pieces, it is well to have two shallowgrooves in corresponding places on that side of the lining blocksto which the forehead piece is to be glued and one on the other

248 MUSEUM IDEALSside. Mark out the lining curve which appears on the upperface of the covered block on the wired side of the correspondingforehead or cheek piece. Spread an even coat of glue, neither toothin nor too thick, over the whole wired surface up to the liningcurve and place this piece upon the covered double lining block,taking care that it is exactly in place. Turn the whole over onthe bed-block and glue the other piece to the other flannel sur-face of the lining in the same way. When the glue has set, re-move the weight or clamps used in the process, take out the lin-ing blocks and trim out the strip of flannel which forms thelunette and which has been left as a stay. The skiascope isthen finished. If the pressure has forced some of the gluethrough the flannel and caused it to stick to the blocks, theymay be freed by carefully inserting a thin knife. But muchthe better way is to Insert strips of paraffin paper in advancebetween the lining blocks and the flannel. The glue will notpenetrate the paper strips, and they can easily be removedafter removing the blocks.