Papers of Marconi's Chief Engineer, Richard Vyvyan, comprising over thirty letters by Guglielmo Marconi, letters by other correspondents including Sir Ambrose Fleming and Vyvyan's journal recording their trial operations; the archive including:

(i) Series of eight autograph letters signed by Marconi ("G. Marconi"), to Vyvyan, one to his wife Mildred, written at the time of the first transmission of telegraph signal from Canada to England; on 5 August 1903 informing Mrs Vyvyan that "I have been working very hard to try and find out what are the somewhat occult causes which make signals good one night and unobtainable the next, and also the reason of the great difference in distance over which signals can be sent by day compared to night. For this purpose I have had to carry out a very great number of tests between this station [Poldhu] and other stations on the east coast and in Scotland, and I believe I have found if not very clearly the cause of the effects noticed at least the means by which to obtain signals across the Atlantic by day as well as by night"; and on 15 May 1904 in a "Private" letter of eight 4to pages providing Vyvyan with "a statement of the results obtained from the working of the Poldhu station during the last voyage of the S. S Campania, from Liverpool to New York" ("...I have undertaken to carry out a series of tests to war ships stationed at different points, the receiving apparatus being taken in charge of by our assistants. I shall try various sending arrangements at Poldhu in connection with these warships, in order, if possible, to gain more information as to the laws governing the transmission of electric waves over sea during day time. We have obtained a very remunerative contract with the Cunard Co. and some other shipping Cos..."), with other letters covering more domestic matters, such as Marconi's marriage ("...It seems rather strange that I should have got married – doesn't it? but I am so glad that I have and we are very happy..."), their respective children, Marconi standing as godfather to the Vyvyan's daughter Mildred, and their life together in a shared house at Cape Breton, some 4o pages, 4to and 8vo, Poldhu, New York, on board RMS Electra, and elsewhere, 1902-1905

(ii) Series of twenty-three typed letters signed ("G. Marconi"), to Vyvyan, a more formal series ("Dear Sir"), written in Marconi's capacity as Managing Director to Vyvyan at Glace Bay, discussing personnel and equipment ("...Since my return here from London a few days ago I have been carrying out some interesting work. We are at present using only about half the available power of the plant, and the results of the programme, according to latest reports, are satisfactory in the light of the arrangements which we are using at this end. I hope that, by the time this letter reaches Glace Bay, you will have received the discs which were sent in charge of the operator of the 'Empress of Ireland' last Friday..."), some 35 pages, 4to, mostly from Watergate House, Adelphi, August 1907 to August 1908 and 10 June 1909

(iii) Vyvyan's illustrated autograph "Notes on Long Distance Wireless Telegraphy and The Design and Construction and Working of High Power Wireless Stations", beginning in 1900 with work on the first trans-Atlantic transmission ("...In March of 1900 Mr Marconi after his invention of transmitting jigger decided that wireless telegraphy across the Atlantic was possible...") and running on up to February 1904; continuation volume lacking, pages numbered to 215, on squared paper, haf calf (worn), folio, 1900-1904

(iv) Nine typed and autograph letters by Sir Ambrose Fleming, co-worker with Vyvyan for Marconi and inventor of the thermionic valve ("...I read of the death of Marconi in a four-days-old London Times newspaper when having tea at Vadheim in Norway... The obituaries which I have seen since return to England of him in the newspapers and magazines do not do justice to the cooperative work of his colleagues or of his contemporaries and I think it may be necessary to repair this omission... I agree with all you say about M. He had genius of a certain kind but he over-reached himself in thinking that he could appropriate the whole credit for wireless..."), nearly 20 pages, 4to, 1901 and 1902, the remainder August to November 1937

(v) Other correspondence, including a letter by Vyvyan to his brother ("...Baby has had the distinction of being the first who has ever had its birth announced by wireless telegraphy..."), and a series to him by Alldin Moore ("...how the dickens is... anyone at the Admiralty to deal with your Company except through you... you were & are the man one could say anything to without the fear of it being brought up in evidence later..."), plus printed ephemera, news clippings ('Television impossible... Official view of B.B.C.'), photographs etc