In another letter Addison writes:--"The business of this is to invite you to a concert of music which I have found out in a neighbouring wood. It begins precisely at six in the evening, and consists of a Blackbird, a Thrush, a Robin-Redbreast, and a Bullfinch. There is a Lark, that, by way of overture, sings and mounts till she is almost out of hearing; and afterwards, falling down leisurely, drops to the ground as soon as she has ended her song. The whole is concluded by a Nightingale, that has a much better voice than Mrs. Tofts, and something of the Italian manner in her divisions. If your Lordship will honour me with your company, I will promise to entertain you with much better music, and more agreeable scenes, than you ever met with at the Opera; and will conclude with a charming description of a Nightingale out of our friend Virgil:-- "'So close, in poplar shades, her children gone, The mother Nightingale laments alone; Whose nest some prying churl had found, and thence By stealth convey'd the unfeathered innocence: But she supplies the night with mournful strains, And melancholy music fills the plains.'" BIRDS' EGGS AND NESTS. The Eggs of Birds are variously tinted and mottled, and hence they become objects of interest to the collector. In this diversity of colour nature has, doubtless, some final object in view; and though not in every instance, yet in many, we can certainly see a design in the adaptation of the colours to the purpose of concealment, according to the habits of the various classes of Birds. Thus, as a general rule, the Eggs of Birds which have their nests in dark holes, or which construct nests that almost completely exclude the light, are white; as is also the case with those Birds that constantly sit on their Eggs, or leave them only for a short time during the night. Eggs of a light blue or light green tint will also be found in nests that are otherwise well concealed; while, on the other hand, a great proportion of those nests that are in exposed situations have Eggs varying in tints and spots in a remarkable degree, corresponding with the colours of external objects in their immediate neighbourhood. Thus, a dull green colour is common in most gallinaceous Birds that form their nests in grass, and in aquatic Birds among green hedges; a bright green colour is prevalent among Birds that nestle among trees and bushes; and a brown mottled colour is found in those Eggs that are deposited among furze, heath, shingle, and grey rocks and stones.