was it used for as a postal service?
Yes, a message may be written on thin light paper, rolled into a small tube, and attached to a messenger pigeon's leg.
Homing pigeon
A message may be written on thin light paper, rolled into a small tube, and attached to a messenger pigeon's leg. 
the number of valence electrons of the germanium element is UNANSWERABLE what is germanium? It is a chemical element with the symbol Ge. is it a metal? It is a lustrous, hard-brittle, grayish-white metalloid. what is its atomic number? 32 who discovered it? UNANSWERABLE where can it be found? In the Earth's crust. what are some of its applications? 35% for fiber-optics, 30% infrared optics, 15% polymerization catalysts, and 15% electronics. what help does it offer in the field of optics? It is useful for wide-angle camera lenses, microscopy, and the core part of optical fibers. what does the last mentioned term refer to? A flexible, transparent fiber made by drawing glass (silica) or plastic. is it used in communication technology? Yes, it is used as a medium for telecommunication and computer networking. how do pigeons affect the former medium? Homing pigeons have occasionally been used throughout history by different cultures. what were other means of communication in early times? Electrical telegraph. who invented the device? Sir William Fothergill Cooke what kind of pigeons are mentioned above? It is a variety of domestic pigeons derived from the wild rock dove.
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Homing pigeon [SEP] Postal carriage
A message may be written on thin light paper, rolled into a small tube, and attached to a messenger pigeon's leg. They will only travel to one "mentally marked" point that they have identified as their home, so "pigeon post" can only work when the sender is actually holding the receiver's pigeons. With training, pigeons can carry up to 75 g (2.5 oz) on their backs. As early as 1903, the German apothecary Julius Neubronner used carrier pigeons to both receive and deliver urgent medication. In 1977, a similar system of 30 carrier pigeons was set up for the transport of laboratory specimens between two English hospitals.