| 摘要 |
To prevent unnoticed penetration of the wall, a sheet of hardened glass (19) is built into it, extending between floor and ceiling. This glass sheet has an electric alarm circuit connected to an alarm device. The alarm circuit is broken when the glass is completely disintegrated, causing the alarm to be released. To comply with normal fire prevention regulations, the wall is completed with an inner, wholly covering sheet of steel plate (23). |
