In the 19th century a popular thing for your desk would be a postal scale, after dealing with your correspondence you could pop your mail onto these small scale to establish the weight, and then place the appropriate stamps on the letter, this way when a member of staff took the mail to the postoffice there would be no need to carry money.
 
A Victorian brass postal scale with engraved postal rates and original weights.
 
Condition is good
 
Dimensions; 19cm x 12cm x 10.5cm high