The main device (symbol) in the Biddulph blazon is the eagle. The two main tinctures (colors) are vert and argent.
The deep green colour that is so often observed in heraldry is more properly known as vert. According to Wade, the use of this colour signifies “Hope and Joy”, but may also represent, rather delightfully, “Loyalty in Love” 1The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P36. It has other names also, the French call it sinople, perhaps after a town in Asia Minor from where the best green die materials could be found 2A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Vert. More fanciful heralds liked to associate it with the planet venus and the precious stone emerald 3Boutell’s Heraldry, J.P. Brooke-Little, Warne, (revised Edition) London 1970, P 27. More strangely, there is some evidence that the term prasin was anciently used, being the Greek for the vegetable we call the Leek!
Argent is the heraldic metal Silver and is usually shown as very pure white. It is also known more poetically as pearl, moon (or luna) 4Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P53. In a sketch or drawing it is represented by plain, unmarked paper 5A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1847, P11.
Where the lion is undisputed king of the animals, the eagle undoubtedly plays the same role in the realm of the birds, its use in this form dating back to at least the Roman period 6A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Eagle. They tend to be illustrated in quite some detail, especially in continental European arms, and have almost as wide variety of postures and accessories as the lion, well illustrated in the reference 7A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P235-238 as well as being just the eagle’s head or eagle’s leg. The symbology of the eagle is deep and complex, Wade devotes several pages to the subject 8The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P72-74, but suffice it say that it has long been associated with Empire and those held in high honour – any armiger would be pleased to have any form of Eagle upon their arms!