Home Index Site Map Up: Paper Navigation
Up: Paper

First: Pocket Hand-Book of Electro-Glazed Luxfer Prisms - Page 1 Last: Pocket Hand-Book of Electro-Glazed Luxfer Prisms - Page 287 Prev: Pocket Hand-Book of Electro-Glazed Luxfer Prisms - Page 87 Next: Pocket Hand-Book of Electro-Glazed Luxfer Prisms - Page 89 Navigation
Handbook: 88 of 287
·1 ·29 ·57 ·85 ·113 ·141 ·169 ·202 ·232 ·260
·2 ·30 ·58 ·86 ·114 ·142 ·170 ·205 ·233 ·261
·3 ·31 ·59 ·87 ·115 ·143 ·171 ·206 ·234 ·262
·4 ·32 ·60 ·88 ·116 ·144 ·172 ·207 ·235 ·263
§5 ·33 ·61 ·89 ·117 ·145 ·173 ·208 §236 ·264
·6 ·34 ·62 ·90 ·118 ·146 ·174 ·209 ·237 ·265
·7 ·35 ·63 ·91 ·119 ·147 ·175 ·210 ·238 §266
·8 ·36 ·64 ·92 ·120 ·148 ·176 ·211 ·239 ·267
·9 ·37 ·65 ·93 ·121 ·149 ·177 ·212 ·240 ·268
·10 ·38 ·66 ·94 ·122 ·150  ... ·213 ·241 ·269
§11 ·39 ·67 ·95 ·123 ·151 §186 ·214 ·242 ·270
·12 ·40 ·68 ·96 ·124 ·152 ·187 ·215 ·243 §271
·13 ·41 ·69 ·97 ·125 ·153 ·188 ·216 ·244 ·272
·14 ·42 ·70 ·98 ·126 ·154 ·189 ·217 ·245 ·273
§15 ·43 ·71 ·99 ·127 ·155 ·190 ·218 §246 ·274
·16 ·44 ·72 ·100 ·128 ·156 ·191 ·219 ·247 ·275
·17 ·45 ·73 ·101 ·129 ·157 ·192 ·220 ·248 ·276
§18 ·46 ·74 ·102 ·130 ·158 ·193 ·221 ·249 ·277
·19 ·47 ·75 ·103 ·131 ·159 ·194 ·222 ·250 ·278
·20 ·48 ·76 §104 ·132 ·160 ·195 ·223 ·251 ·279
§21 ·49 ·77 ·105 ·133 ·161 ·196 ·224 ·252 §280
·22 ·50 ·78 ·106 ·134 ·162 ·197 ·225 ·253 ·281
·23 ·51 §79 ·107 ·135 ·163 §198 ·226 ·254 ·282
·24 ·52 ·80 ·108 ·136 ·164 ·199 ·227 ·255 §283
·25 ·53 ·81 ·109 ·137 ·165 ·200 ·228 ·256 ·284
·26 ·54 ·82 ·110 ·138 ·166 ·201 ·229 ·257 ·285
·27 ·55 ·83 ·111 ·139 ·167 ·202 ·230 ·258 ·286
§28 ·56 ·84 ·112 ·140 ·168 ·203 ·231 ·259 ·287
 
    Solution.--Taking ten feet (height of prism plate above pavement) off the height of the building opposite, we find the zenith-tangent to be 0.36, from table of zenith-tangents, column headed 70 (height of building less 10 feet) and row 25 (width of alley). Turning to page 189, Table of Luxfer Prism Prescriptions, corresponding to highest light assumed horizontal and to the first row corresponding the nearest to our zenith-tangent of 0.36, and to column 45° lowest light below horizontal, we find that canopy A must be used. In order to find the area of this canopy, we turn to page 211, table of Luxfer Prism areas, corresponding to room width 40 feet, and to the table headed "For Storage," we select the columns headed A, 0.4 because 0.4 is nearest our zenith-tangent. Here we find 95 square feet needed for a room 50 feet long. We may therefore order one continuous canopy 2 feet 6 inches deep, by 40 feet width of room, if we have no columns in the way, or we may divide this area into single canopies mounted separately over their respective openings.

Reveals.

    Fig. C illustrates a section through a window having a heavy cap or reveal. It is evident that this shadows the upper part of the window from the sky, and interferes with the work Section through window having heavy cap or reveal of the prisms placed therein. There are two methods of treating this case which prove satisfactory, either increasing the depth of the prism plate enough to make up for the loss arising from the shadow, or setting out a prism plate called FORILUX, in a separate frame flush with the face of the wall. In this latter case about 10 per cent should be added to the area of the prism plate to make up for the light lost in passing through the undisturbed plate glass in the sash behind the prism plate. Fig. D shows the method of obtaining the correcting factor in case it is desired to install the prisms under the reveal. AB is the depth of the prism plate, the area of which is specified in the table.
  Pocket Hand-Book of Electro-Glazed Luxfer Prisms - Page 88