No explosives must be shipped from, discharged at, brought to, or deposited upon any wharf or place except such place which the port captain or his authorised deputy must from time to time direct and such wharf or place must be barricaded off to the satisfaction of the port captain or his authorised deputy and the quantity of explosives to be conveyed to and allowed on such wharf or place must be regulated by the port captain or his authorised deputy; no other goods or articles must be handled in such wharf or place at the same time with explosives, and no persons other than those actually engaged in or superintending the work of loading or unloading must be allowed within the barricades.