Here is an illustration of a CD 146 from the Central Electric Company 1906 catalog, courtesy Mr. N. R. Woodward. It appears to be a double petticoat style of the CD 143 single petticoat, both having the patented ribbing.

This is covered in Design Patent 31,799 which can be viewed at

http://reference.insulators.info/patents/detail/?patent=31799&type=D

To date, no specimens have been found and thus this CD is not included in any of the hobby reference material.