Bash script to download sequentially numbered images
I would write it this way:

#!/bin/bash

url_template="http://150.216.68.252:8080/adore-djatoka/resolver?url_ver=Z39.88-2004&amp;svc_id=info:lanl-repo/svc/getRegion&amp;svc_val_fmt=info:ofi/fmt:kev:mtx:jpeg2000&amp;svc.format=image/jpeg&amp;svc.level=6&amp;rft_id=http://150.216.68.252/ncgre000/00000012/00011462/00011462_ac_%04d.jp2"

for i in {1..584}; do
    wget -O $(printf '%03d.jpeg' $i) "$(printf "$url_template" $i)"
done


Specifically,


At first glance, I thought that $urlFirst and $urlSecond were two URLs, until I figured out what was happening.
If there is another leading 0, then %04d is more appropriate than %03d.
The web server isn't going to care about the order of the parameters in the query string.  For the benefit of humans, though, it would be nicer to put the parameter that changes either first or last.
Fewer variables is nice.  I do everything by interpolation.  You can get a feel for what the wget command does, without tracing which variable came from where.