Respecting the _African Exploring Expeditions_, Miss Overweg (daughter of one of the travellers) and the Chevalier Bunson, have received in London interesting letters, stating the continued success of the adventurous scholars. Previous to the 6th of August Dr. Overweg had safely joined his companion, Dr. Barth, at Kuka. The latter started on a highly interesting excursion to the kingdom of Adamowa, while the former was exploring Lake Tsad. The boat, which had been taken to pieces in Tripoli, and during a journey of twelve months had with immense trouble been carried on camels across the burning sands of the Sahra, had been put together and launched on the lake; and the English colors were hoisted in the presence, and to the great delight, of numerous natives. Dr. Overweg, in exploring the islands of Lake Tsad, had been every where received with kindness by their Pagan inhabitants. * * * * * The _Courrier de la Gironde_ states that a civil engineer of Bordeaux, named De Vignernon, has discovered the perpetual motion. His theory is said to be to find in a mass of water, at rest, and contained within a certain space, a continual force able to replace all other moving powers. The above journal declares that this has been effected, and that the machine invented by M. de Vignernon works admirably. A model of the machine was to be exposed at Bordeaux for three days, before the inventor's departure with it for London. * * * * * The British Government has granted 1500_l._ to Colonel Rawlinson, to assist him in his researches among the Assyrian antiquities; and 1200_l._ for the publication of the zoology and botany collected during the Australian expedition of H.M.S. _Rattlesnake_, commanded by the late Captain Stanley, son of the late Bishop of Norwich. * * * * * The _Museum_ of Berlin says that a Prussian has discovered in the ruins of Nineveh, a basso-relievo, representing a fleet of balloons--another proof that "there is nothing new under the sun."