A good period source would be " 'The Workwoman's Guide', by A Lady" (c. 1838-40) You could probably find a reprint with a little searching online, or Google Books has a digital copy online which can be downloaded as a .pdf file (it appears some pages are missing from the preview though, don't know if there are pages missing from the .pdf file).
Some examples of the caps you're speaking of can be found illustrated in Plate #19 toward the back of the book (the plates start after pg. 300), with the general construction directions located in the text of the book, approx. pg. 153-158.
Good luck to you.
“… and know that it was in California we learned the art of making long journeys with safety, to endure privations with cheerfulness, and to thrive under the most adverse circumstances, and these have enabled us to make strides in war which may seem gigantic to the uninitiated.”
(excerpt from a letter from Gen. W. T. Sherman to Governor Frederick Low of California, dated Goldsborough, N.C. March 24, 1865)