The first intimation which the public had of the existence of the conspiracy was the publication on the 8–20 June, in the St. Petersburg _Journal_, of an address presented to the emperor at Helsingfors, during his late visit to Finland; the subject was again referred to in the succeeding number of the 15–27 of the same month. I herewith transmit you both these numbers. From the desperation of the Poles, and their determined character, this information has excited considerable alarm in St. Petersburg. The people here, whilst they admire and respect the emperor as the author of their security and prosperity, look with fearful apprehension to the future, in the event of his assassination. The heir apparent is yet a minor, and although he possesses a most amiable disposition, it is believed he is deficient both in talent and strength of character. The Grand Duke Michel, who would become regent, is as universally disliked as the emperor is esteemed. Indeed, in such an event, many of the foreigners in St. Petersburg, knowing the deadly hostility felt against them by the lower orders of Russians, would entertain serious apprehensions for their lives and their property. Such is the miserable condition of despotism; and such is the feeling here, at the very moment when this government, more by its superior policy than its power, has acquired a commanding influence throughout Europe. Still greater precautions now exist than did formerly, in regard to the admission of strangers into the country. The emperor no longer appears in the streets like a private citizen. It is said that he is always surrounded by guards. But from what I have heard, he rather submits to these regulations of his ministers than approves of them himself. He is a bold and fearless man, and manifests no apprehension whatever. If the Poles have determined to play the part of Scaevola, he at least will not enact that of Porsenna. Three of the conspirators have been seized in Russia. After all I cannot feel that there is much danger. I send you the _Journal_ of yesterday, containing our latest news from Constantinople. This despatch will be carried to London by Mr. Gibson, our consul. He has been ill for some time, and his disease is, I fear, now approaching its crisis. He is very feeble, has a bad cough, and throws up much blood. His physician informed him that his only hope was to leave St. Petersburg, and that immediately. Mr. Clay will perform his duties during his absence, and we are both happy to render all the services in our power to so worthy a man and so good an officer. After having written the foregoing, I had the pleasure of receiving your Despatch No. 11, dated on the 30th April. It has been long on the passage. By the Hamburg _Reporter_ received on the 29th ultimo, we had New York dates, via London, up till the first of that month. On the 19th of July, Mr. Buchanan received the melancholy news that his mother had died in the previous May.