The following images are available from the "William Gray Purcell Job Files" digital images database served by the IMAGES system at the University of Minnesota Libraries.  These thumbnail links go directly to their access and use statements for each image.  A (usually) higher resolution image can be downloaded from the citation display page; such files may show highly useful detail, but are often 200-300K in size.  Because their web site is a separate resource, the links here open new browser windows.