Midshipmen wore a double-breasted coat with a rolling collar -- the undress of passed midshipmen -- and with an anchor of buff cloth inserted in either side of the collar.

U.S. Navy Midshipman
Model 1841 undress coat

As had been true for many years, the regulations of 1841 ran consistent to the nine-button arrangement for senior commissioned officers, and to the four-button pattern for the sleeves and pockets of captains, with three buttons for commanders, lieutenants, medical officers, and pursers.  At the same time the coats of captains and commanders had become plain without lace or embroidery, those of medical officers had grown more elaborate.  The border of leaves and acorns specified for full dress in 1830 had been retained, but the device of 1832, the branch of live oak, was omitted.  The band of embroidery was removed from the cuffs of surgeons.  Instead, surgeons wore three strips of one-and-one-half-inch gold lace around the cuffs, the three buttons being between the upper two strips.  Passed assistant surgeons had two strips of similar lace, and assistants, one.  To those not familiar with the regulations, the well-laced surgeon might appear to be the most senior officer of the United States Navy.  His cuffs showed lace, while those of a captain were plain.  In most countries, rank was judged by the maount of lace or embroidery: the more the higher the rank.

Pursers (officers who paid and fed the crews, and procured clothing and supplies) retained the same embroidery as authorized in 1830, except that the device of the Purser Department, the cornucopia, was replaced by a strip of live-oak leaves and acorns of the same pattern as tha around the full-dress collar.  With the regulations of 1841, chaplains were finally permitted to wear a naval uniform: the undress coat of a lieutenant, with a black felt collar and cuffs.  Chaplains had finally received recognition as commissioned officers, with the double-breasted coat containing nine Navy buttons in each row and three on the cuffs and under the pocket flaps.

Professors of Mathematics and secretaries to commanders of fleets and squadrons were also ranked as officers.  A secretary was directed to wear a double-breasted, rolling-collared, undress coat of a lieutenant, with two rows of nine buttons each, but with none on the cuffs.  Professors and clerks wore the same coats as secretaries, but with only seven buttons in a row.

U.S. Navy Master
Mode 1841 undress coat

This daguerreotype shows a Navy Master.  Masters wore for dress the undress coat of the senior officers.  On the collar were two loops of gold lace, each four and one-half inches long, with a button in each loop.  Second masters wore the same coat, but with a single loop and button.  The undress coat for all officers entitled to wear the standing-collar full-dress coart was of dark blue, lined with the same, and with a rolling collar.  The number and location of buttons was the same as in full dress.

The 1841 regulations expanded the system of showing some form of rank device on epaulets.  Previously, only a  commodore had been assigned a device -- a silver star.  The new regulations directed all captains to wear  aplain silver anchor and eagle on epaulets, and commodores a star above the anchor-eagle device.  These regulations also expanded the shoulder-strap system to incorporate some indication of rank.  Captains were instructed to wear blue cloth straps, two and a half inches long and half an inch wide, with gold-embroidered edges.  Commodores displayed the star in the center of the straps; for captains the straps were plain.  Commanders and lieutenants wore gold lace straps, the same size of those for captains, but without devices.  Since lieutenants were entitled to but one epaulet, they wore the strap on the right shoulder.  From this humble beginning was developed the U. S. Navy's system of shoulder straps which came into full use during the Civil War. 

All officers except professors, clerks, and the forward warrant officers were permitted to wear cocked hats.  The excepted officers wore blue cloth caps with blue bands.  The use of bullion loops over the cockades introduced in 1830 was expanded. Captains and commanders retained the loop of six bullions, the center pair twisted; lieutenants, masters, and passed and other midshipmen now had  alook of four bullions, the center pair not twisted.  

Just before the Mexican War, in 1845, uniform regulations were modified authorizing lieutenants to wear two plain gold epaulets.  Commanders were directed to wear a plain silver anchor device.  Captains other than those in command of a squadron now displayed a silver spread eagle.  The Navy's first cap device, the anchor and star for midshipmen and the anchor for midshipmen, were removed from the front of the blue cap.  All midshipmen were now permitted to wear a gold lace band an inch and a half wide, the same as authorized for captains, commanders, and lieutenants.  Lighter-weight frock (undress) coats of "dark blue summer-cloth" were authorized for warm climates and straw hats were permitted.  The body of the hat was to be six inches high, and the brim three and a half inches wide.   

The assignment in 1846 of relative rank to medical officers, and in 1847 to pursers, led to further modifications by orderf of Secretary of the Navy John T. Mason on May 27, 1847.  Now medical officers and pursers were permitted to wear epaulets similar to those of the sea officers with whom they had been given relative standing.  However, the epaulets were of a different pattern, for the crescents were to be solid and bright, instead of embroidered.  The bullions of the epaulets of surgeons and pursers of more than twelve years' standing were to be the same as those of comamnders with whom they ranked, a half inch in diameter and three inches long.  For surgeons and pursers of less than twelve years' service, the bullions were to be like those of lieutenants -- three inches long, but only t