We live in a house built in 1906. We've had fewer "incidents" in this old home than in newer houses. I'm not sure about 1940's but here 1900's houses are all plaster and lathe and the woodwork (baseboards etc) are all perfectly aligned as well as firmly attached so it is virtually impossible to get inside the walls around pipes or outlets (especially when you must get in to repair!). One problem area we found:The kitchen was remodeled in our house around 1950 we suspect. During the remodeling a new lower ceiling was also put in. We found areas in the top of the cabinets that accessed the space between the new ceiling and the old tin ceiling - so when looking - look UP as well as DOWN! Charlene (We rewired the whole house with a wirefeeder *before* we found out that ferrets were skilled at running wires. If we had only known!) [Posted in FML issue 1278]