A QUESTION OF MOTIVE
As for the Coulombs' motive in all of this, one deduces that it was progressively three-fold:
1. As originally conceived, it seems to have been a half-baked scheme to convert the Shrine into a conjuror's box for the delivery of forged Mahatma notes framed to part the faithful from their Rupees and to enrich the scheming pair after H.P.B.'s then-forthcoming departure from India. This idea was probably born at the Convention of December, 1883, when 500 Rupees passed out of the Shrine and into possession of Mr. P. S. Row.  And the idea of adapting the Shrine may have been conceived in Mons. Coulomb's ruminations during his repair work in H.P.B.'s rooms that same month. Here the incentive factor was surely the arrival at Headquarters, between November, 1883, and H.P.B.'s departure, of "the millionaire, Mr. Lane-Fox" (81) and wealthy Prince Harrisinghji Rupsinghji, from whom Mme. Coulomb, without losing time, admittedly tried to get 2,000 Rupees (74-5, 79-80) --- not to forget Dr. Hartmann from Colorado with "silver-mine stock" in his pocket.
2. When this idea failed, seeing that the use of the Shrine for fraud proved to be not only too impractical but the work of conversion too dangerous to complete, there remained the possibility of extorting sums of money from the wealthy Theosophists present and others, by threatening a public "exposure" of Theosophical phenomena, using the devices worked up in H.P.B.'s rooms just for this purpose (sliding panel in almirah, freshly-repaired marks of "screw-rings" in the ceiling, etc.). Mme. Coulomb (in a passage Hodgson prudently suppressed) admits that, at the last, hoping to go to America, she demanded "our journey paid and 3,000 Rs. in hand" - though "this was not for the sake of money, but to have means to come back in case Madame Blavatsky accused us of having done the sliding-panels, etc., in her absence" (112) --- !
3. When the preparation of trick apparatus required by this scheme was cut short by Damodar Mavalankar's exposure of the Coulombs' "confidential communication," given him only to stall for time and completion of the secret work, and when Damodar's exposure of the Coulombs was backed up by Mme. Blavatsky's telegram of adamant farewell, "Sorry you go, prosper" (111), nothing was left except for the conspirators to throw themselves on the mercy and generosity of the Christian missionaries, for what little profit that might mean. It did not prove to be much, only 150 Rs., which was a pity, since Mme. Coulomb, her greed unsatiated, set about on her own to publish her story in saleable form, with the result that her pamphlet of the following November remains the best answer one could conceivably give to any critic of Mme. Blavatsky --- by anticipation, a calamitous exposure of the "Hodgson Report"!
And Hodgson's motive? We may confidently leave that to the future and to the inexorable verdict of history.
 Report of the Result of an Investigation, etc., p. 64.