…but due to a Wordpress updating foul-up, Silverbased.org may not be restored for some time. There are some Wayback Machine copies available, but you might need to click around to different dates in order to see all the images.
The URL above refers to the post Mercury Battery Replacements?
The followup post can be seen at Quirks of the Zinc-Air Cell, Part 2
A related post on separate light meters is Light Metering