This is simply Sefer Tehilim – the Book of Psalms, published in London by Samuel Bagster and Sons. I particularly like this edition for two reasons. One is that the Hebrew root of each word is designated by being printed in black, while the other letters are hollow. This makes the entire book a grammatical tool. The second is the very literal English translation, which is printed, word by word, from right to left, to follow the Hebrew. Look below and you will see a book if typographical achievement.
And finally, as an added nice thing, my copy was owned (and is signed) by Moses Gaster. Moses Gaster (1856 – 1939) was a Roumanian scholar who became the “Chacham” – the Rabbi of the Spanish and Portuguese (i.e. Sephardi) Jewish communities in London. He was a recognized historian and Hebrew linguist.