section 12 of General clauses Act 1897

Section 12 in The General Clauses Act, 1897

12. Duty to be taken pro rata in enactments. —Where, by any enactment now in force or hereafter to be in force, any duty of customs or excise, or in the nature thereof, is leviable on any given quantity, by weight, measure or value of any goods or merchandise, then a like duty is leviable according to the same rate on any greater or less quantity.

The said provision reads as above. But what are the facts as well the context for this query? 

It is a cerntral act:

Section 12 in The General Clauses Act, 1897

12 Duty to be taken pro rata in enactments. —Where, by any enactment now in force or hereafter to be in force, any duty of customs or excise, or in the nature thereof, is leviable on any given quantity, by weight, measure or value of any goods or merchandise, then a like duty is leviable according to the same rate on any greater or less quantity.

To your subsequent question, the section 14 of the same act clearly explains your doubt, which s reproduced belwow:

14. Powers conferred to be exercisable from time to time.—(1) Where, by any 1 [Central Act] or Regulation made after the commencement of this Act, any power is conferred 2 ***, then 3 [unless a different intention appears] that power may be exercised from time to time as occasion requires. (2) This section applies also to all 4 [Central Acts] and Regulations made on or after the fourteenth day day of January, 1887.

I have reproduced the contents of section 14 of the act, which clearly covers your question. read it fully and properly to understand the provisions of law in this regard. 

Very well explained and advised by experts, I concur.

Instead of giving examination it is better to be specific to your problem / dispute

Section 10 is about computation of time, and section 11 is about Measurement of Distances, and Section 12 is about Duty to be taken pro rata in enactment in the GCA. I think the specefic fact is missing in your query. 

If you are a student then this query is OK. But if not, I suppose that you are trying to test the interpretational abilities of others just to satisfy your ego.

Anyway, 

1. You should know the usage of General Clauses Act 1897.

2. It is a settled rule of law that if a term a defined under a specific statute, then only that definiton is subsituted it that statute wherever that "term" appears but If not defined in that statute or not referenced there, then subtitute the meaning of that "term" as defined in GCA. 

I hope this will satisfy your quest.

Thank you.