PER CURIAM.
The trial judge's rulings from which defendant appeals not having been shown to be prejudicial and a review of the record disclosing neither prejudice nor error as alleged by appellant in the court's comments during trial, the judgment in favor of plaintiffs is affirmed.
Plaintiffs also urge that under the recently adopted R. 4:42-11(b) (effective January 31, 1972) interest should be allowed on the amounts of the judgment from February 5, 1969, the date of the institution of the action. We hold this rule does not apply retroactively to judgments entered prior to its effective date.