Keep in mind that manufacturers changed their marks quite often.
While a guide would be helpful there are few authors that have had the energy to create a complete listing of pottery marks.
1925, decorated by Sadie Irvine with dogwood blossoms, blue, green, pink and yellow underglaze, base of each marked with Newcomb cipher, decorator’s mark, Joseph Meyer’s potter’s mark, reg. Sold on February 3, 2007 for ,900.00, 1908, decorated by Marie de Hoa Le Blanc with freesia modeled in relief, blue, dark green, yellow and white underglaze, base marked with Newcomb cipher, decorator's mark, Joseph Meyer's potter's mark, reg.
Ryan with yucca in underglaze blue and white, base marked with Newcomb cipher, decorator's mark and date, and Joseph Meyer's potter's mark, height 9 3/4 in. A Newcomb College Art Pottery Matte Glaze Vase, 1916, in the classic tapering shape with blue matte glaze over a raised wisteria blossom and leaf design, by Henrietta Bailey, registration number HZ 84, height 8 in. A Newcomb College Art Pottery High Glaze Inkwell, 1910, painted with a band of children with outstretched arms in blue and green underglaze, decorated by Louise Ayars, registration number EB41, height 2 3/8 in., diameter 2 7/8 in. A Newcomb College Art Pottery Tile, 1933, sculpted with the Newcomb fountain and Louisiana irises, by Sadie Irvine, registration number UO53, height 6 in., width 4 3/8 in., depth in. Sold for ,315.00 on June 25th, 2011, 1912, decorated by Anna Frances Simpson with landscape of moss-laden live oak trees, dark blue and green underglaze, marked with Newcomb cipher and decorator's mark, reg. 1905, decorated by Henrietta Davidson Bailey, with an incised design of stylized oak trees in blue, green and yellow underglaze, base marked with Newcomb cipher, decorator's mark, Joseph Meyer's potter's mark and "Q" for buff clay body, height 5 in., width 6 1/4 in. Sold on February 23, 2008 for ,213.00 A RECORD PRICE FOR A PIECE DECORATED BY BAILEY AT ITS TIME OF AUCTION, 1915, decorated by Alma Mason with Louisiana irises modeled in low relief, matte glaze with blue, green, pink and white underglaze, base marked with Newcomb cipher, decorator's mark, Joseph Meyer's potter's mark, reg. It can be difficult for a novice collector to be sure whether they are looking at an authentic or fraudulent maker's mark.Learning the unique signature of each manufacturer takes time but is certainly worth the effort.
Newcomb College Pottery was founded in 1895, at Sophie Newcomb College, New Orleans, Louisiana, by Ellsworth Woodward and William Woodward.