"Once libraries had outgrown the cupboards or chests of earlier times, a separate library room became a common feature from the 12th century onward. The arrangement of a typical later medieval library is known from some surviving examples, although the fittings in all of them have been altered over the centuries. In general the room would be long and fairly narrow, built on the second floor to protect against damp and give adequate light. Ranged along the walls between the windows and projecting at right angles from them would be long lecterns for reading the books. The books themselves would lie flat on shelves underneath the lecterns, to which the reader (standing up) would bring them on chains. There was often a written shelf list affixed to the end of each lectern to show what books were on the shelves. This would be, in effect, an extract of the catalog, which continued to reflect the actual physical grouping of the codices. The common libraries of convents and colleges would usually be kept locked, the key in possession of the librarian, who could variously be called the armarius, cantor or precentor, librarius, custos librorum, or bibliothecarius. The position and duties of the librarius were laid down in some detail by Humbert of Romans, general of the Dominicans, in his Instructiones officialium from around 1260. and these were often adapted and expanded in later library regulations. Not all the books in an institution were chained; It was the custom in colleges and friaries, as it was earlier and continued to be in monasteries, to make an annual distribution of books to fellows, brothers, or monks for their learned or edifying reading. These loans could on occasion stretch out over many years, or even a lifetime" (M. Davies, "Medieval Libraries" in D. Stam (ed.) International Dictionary of Library Histories  107).