There is hereby created a special fund in the treasury of the city to be designated and known as the policeman’s retirement fund for the purpose of providing retirement pay and other benefits for paid policemen, as defined herein, becoming aged or disabled while in the public police service of said city and also providing for their dependents. Such fund shall consist of all moneys accruing under the provisions hereof, all appropriations thereto, all contributions to said fund, donations, properties, and securities acquired by investment or otherwise, and interest earned, shall, commencing with the effective date of such fund, become a part thereof.