Abstract: An above-ground secondary containment unit for storage tanks is comprised of a rigid base and upwardly extending side and end walls. Side cover shields are mounted to the top of the side walls by way of hinges and are intended to contact a side surface of the storage tank thus minimizing or preventing the entry of precipitation or debris into the unit while the tank is in place. End cover shields are mounted to the top of the end walls using a nut and bolt arrangement and slots in the shield allowing for lateral adjustment of the shields with respect to an end surface of tanks of varying sizes and configurations. These shields similarly minimize or prevent the entry of precipitation and debris into the unit. The walls of the unit are tapered so that one unit may be nested within another similarly shaped unit for convenient storage and to permit shipment of multiple units at the same time.

Abstract: A microfilm camera which is adapted to photographing images on a reduced scale of documents placed on a support table and to photograph a mark also on the film in the vicinity of each image thereon so that the location and/or size of the original image corresponding to the document photographed can be located from the size and location of the marks by automatic retrieval equipment. When a bad or unsatisfactory exposure is made, the operator merely presses the appropriate button(s) and the unwanted image on the film does not receive either an image address or an image mark and for all intents and purposes, the image is "lost" on the roll of film. The unwanted image is on the roll of film, but it cannot be automatically retrieved because the image does not have an image mark associated with it. This error correction is accomplished by having the document photographed and the film moved a distance of at least one image frame before the image mark and image address are applied to the film.