we're talking about days here, not hours

actionpack/lib/action_view/helpers/date_helper.rb

@@ -501,7 +501,7 @@ def select_hour(datetime, options = {}, html_options = {})
       end
 
       # Returns a select tag with options for each of the days 1 through 31 with the current day selected.
-      # The <tt>date</tt> can also be substituted for a hour number.
+      # The <tt>date</tt> can also be substituted for a day number.
       # Override the field name using the <tt>:field_name</tt> option, 'day' by default.
       #
       # ==== Examples