Scooby puts on Velma's glasses to get a better look at the chains, but this makes no sense. From the dialogue whenever Velma loses her glasses ("My glasses! I can't see a thing without them!") at least implies that she is severly myopic (near-sighted). This may seem irrelivant, but perscriptions for people with myopia make things appear smaller! If he wanted to get a better look, he would have been screwed over using Velma's glasses!