It is unlawful for any person to coast or slide with any sled, sleigh, toboggan or vehicle upon any public street, avenue, sidewalk or alley within the city; provided, however, that the city council, by public notice or proclamation, may authorize the use of certain streets for coasting during the winter season. During the period for which such notice or proclamation shall be issued coasting and sliding upon such streets as may be designated by the proclamation or notice shall be permissible. (Prior code §12-9)