"If this work could be discovered, it might, he thought, in all probability be restored. Some of the country people were therefore seized, and, inquiry being made of them, the line of the canal was pointed out, and the place shown at which it had been derived from the Nahr-Malcha."
The exclusion of "was" is actually an example of Gapping, a form of Elliptical Construction. Ellipsis is almost, but not quite, the opposite of Parallelism; Ellipsis means leaving out duplicated information, while Parallelism is about deliberately adding in duplication for emphasis.
It is possible that you may be inferring Parallelism from the use of both "pointed out" and "shown" - these are both phrases with similar meanings, and can be used for Parallelism. However, they are not being used here to support a common noun/verb, to provide synonymous expression of similar concepts, nor even to contrast antithesis. It also doesn't help that the second clause ("the place shown at which it had been derived from the Nahr-Malcha") contains a lengthy restrictive clause following the verb. All you have here is a list of information gathered from the questioning.
You could adjust the sentence to invoke more parallelism, by connecting both concepts to a single verb ("...and, inquiry being made of them, they pointed out the line of the canal, and the place at which it had been derived from the Nahr-Malcha"), but the excessive length of the second phrase makes this weak Parallelism