apologies if some of the following has repeated what has been said already or crossed with more recent posts - twice I've tried to post but keep getting thrown out by being pipped to the post - it's getting late and hope that amending isn't essential.
regret that my potential to help here has long since expired, and my input (quoted in part by above by m) was limited and lacked any conclusion................but I was still curious as to the origins and provenance etc. of the olive, lion-prunted bowl, in Cottle - page 74 - bottom left of the smaller picture. So I sent an email to Tyne & Wear Museums to enquire as to its whereabouts and to ask for a bigger picture.
The lady's name now escapes me, and in the absence of a reply I deleted the email, unfortunately
- at the time she seemed keen to be helpful and promised to get back to me - but that was many months ago now, and can only assume that she failed to locate the piece. Could always try again.
There are difficulties with attribution for this type of late C19 Venetian Renaissance revival style - Simon Cottle himself said.... "now believed to have been made by this studio" - so he seems to be acknowledging some doubts as to accuracy of information..............and the similarity to much material produced by Salviati, makes for uncertainly of origin. Of course, it may well be that since the author's book is entitled 'Sowerby - Gateshead Glass', then we are perhaps meant to assume that all pieces shown in this author's book are from that factory, without exception.
Cottle's 'group of opalescent free-blown glass in Venetian style, c. 1878' - the larger picture on page 74, is very much what you imagine to be pure Salviati, and might well be pieces made by the ex Murano employees employed by Sowerby around that time. None of these pieces appears to show any rim colouring - this fact may indicate a Sowerby origin - but only guessing.
The smaller picture on page 74 (which includes the bowl with lion prunts) are pieces with pincered, trailed streaked colours, tinted and aventurine decoration, plus crimp formed rims, and appear to me to be a mixture of 'early Egyptian, Roman and Venetian glass styles'
Simon Cottle lumps all of these 'early Egyptian, Roman and Venetian revival styles' into what he calls the first of two distinct phases in the life of the Ellison Works studio - c. 1870 - 1878.............. the second phase he describes, generally, as
aesthetic glass - the Clutha and Dresser forms
It may be that it's the slightly later Clutha and Dresser designs only that may correctly be called art glass, with the earlier Venetian etc. material being described as 'revival' pieces.
In addition to the original free-blown Venetian revival series, Sowerby then produced their mould-blown 'Venetian series items' c. 1878 - recognizable by their olive and clear bodies and turquoise coloured rims - and if I have it right, these are called 'new style aesthetic'.
The last of Sowerby's studio production with a claim to inspiration from Venice, looks to be the white and blue opaque bodied wares c. 1880 - described as Venetian and Near Eastern forms - in appearance more like pottery than glass.
None of which helps John remotely.......... other than to repeat that, since none of what we assume are Sowerby opalescent free-blown pieces (Cottle page 74) show aventurine or coloured rims, then Ivo's Salviati suggestion of origin would look to be more likely.............. but who knows
all credit for the above information etc. must go solely to....... .Simon Cottle's book - 'Sowerby - Gateshead Glass' - TYNE and WEAR MUSEUMS SERVICE - 1986.