Final answer:
The significance of the 1st use of superimposition comparison in the court case involving Isabella Ruxton and her maid is that it provided compelling evidence and helped establish the identity of the culprit.
Step-by-step explanation:
The significance of the 1st use of superimposition comparison in the court case involving Isabella Ruxton and her maid is that it provided compelling evidence and helped establish the identity of the culprit. Superimposition comparison is a forensic technique used to compare two images, such as fingerprints or footprints, by overlaying them to see if they match. In this case, the superimposition comparison was likely used to compare a footprint found at the crime scene with the maid's footprint to determine if she was present.