Immagini

DESCRIZIONE

Questo microscopio, definito nel vecchio inventario "Grande microscopio di Nachet con accessori il tutto raccolto in una cassetta di mogano", è conservato nella sua custodia rivestita all'interno con stoffa. La base metallica, a forma di "U", sostiene due colonnine di ottone alle quali è avvitata la parte principale dell'apparecchio, che è inclinabile (Vedi ref-1).

Su un piatto circolare di ottone, con un foro centrale di circa 2.5 centimetri, si possono appoggiare e fissare con apposite pinze i preparati in esame, che vengono illuminati per riflessione da uno specchio piano regolabile.

Lo strumento è munito di oculare con una manopola per la messa a fuoco.

La custodia del microscopio ospita diversi accessori, alcuni in due cassette portaoggetti accomodate una sopra l'altra:

1. 6 obiettivi in una scatola chiusa
2. Anelli, porta obiettivi, pinze
3. 2 oculari

Nel luglio 2010 l'appassionato collezionista di microscopi antichi Jeroen Meeusen, molto esperto in materia, visitò il nostro Museo: lo ringraziamo moltissimo per le notizie che ci ha dato e per la relazione scritta, che riportiamo integralmente qui di seguito.
"The Nachet microscope initiated my visit as I suspected that this was the microscope acquired by prof. Gilberto Govi for the Gabinetto di Fisica in 1862. I own a letter written by prof. Andrea Naccari, dated “10 Luglio 1887” regarding a “microscopio di grande modello costruito del Nachet acquistato dal Prof. Gilberto Govi per questo Gabinetto di Fisica nell'anno 1862”. Please find a scan of the letter at the top of this page: http://www.meeusen.com/marzari/ Your microscope is signed on the base: “Nachet et Fils, 17 rue St. Séverin, Paris”. By 12 February 1862 Nachet had moved from the Rue Serpente to the Rue Saint-Séverin. It is therefore perfectly possible that your microscope was acquired in the year 1862.
Naccari describes in great detail the substage condenser coming with the microscope by Govi. This information was of great interest to the recipient of Naccari's letter, Alfred Nachet, as Ernst Abbe (re)introduced this type of condenser in 1873 and it became known as the ‘Abbe condenser'. Today, this type of condenser is still referred to as ‘Abbe condenser'.
Your type of microscope was for the first time described in Nachet's 1863 sale catalogue as “microscope grand modèle perfectionné”. Please find a scan of the 1863 Nachet catalogue here: http://www.meeusen.com/marzari/ It was still offered in the 1871 catalogue, but disappeared from the 1872 catalogue. Only very few of these microscopes are recorded, one of them is in the Accademia di Agricoltura di Torino. Some of these ‘top of the line' microscopes came with the pre-Abbe condenser; the example of the Accademia di Agricoltura doesn't, but yours does. As a result few pre-Abbe condensers are known. I have only seen four examples so far. The description given by Naccari of the condenser perfectly fits the condenser that comes with your microscope. Naccari included a drawing of the diaphragm that was present below the bottom lens. This diaphragm was intended for oblique illumination and is present with your microscope. This is a photo I took on my visit showing the peculiar diaphragm in place, exactly as Naccari described it: http://www.meeusen.com/marzari/PICT6334.JPG.
Naccari mentions an additional device (http://www.meeusen.com/marzari/P1124528_small.jpg) for holding condensers, with a rotating diaphragm. This is still present with your microscope and is a quite ordinary device as it comes with all large Nachet microscopes. Contrary to what Naccari believed, it is not to be associated with the pre-Abbe condenser described by Naccari.
I would strongly suggest that your Nachet microscope is the one that was purchased by Gilberto Govi in 1862."

OSSERVAZIONI

ISCRIZIONI

1. Incisione sulla base: NACHET ET FILS¶
   17 rue St Séverin¶
   Paris

BIBLIOGRAFIA

• [1] A. Ganot, "Traité Élémentaire de physique", Paris, 1868, Pag. 504

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