project　12　to　18　inches　at　each　end　beyond　the　line　of
  the　wall。　Let　the　passage　ends　be　entirely　given　to
  either　window　or　glass　door。　Twenty…four　pairs　of
  trams　run　across　the　room。　On　them　are　placed　56
  bookcases；　divided　by　the　passage；　reaching　to　the
  ceiling；　each　3　feet　broad；　12　inches　deep；　and　separated
  from　its　neighbors　by　an　interval　of　2　inches；
  and　set　on　small　wheels；　pulleys；　or　rollers；　to　work
  along　the　trams。　Strong　handles　on　the　inner　side　of
  each　bookcase　to　draw　it　out　into　the　passage。　Each
  of　these　bookcases　would　hold　500　octavos；　and　a　room
  of　28　feet　by　10　would　receive　25；000　volumes。　A　room
  of　40　feet　by　20　（no　great　size）　would　receive　60；000；
  It　would；　of　course；　be　not　properly　a　room；　but　a
  warehouse。
  End